Revert Section Z default value

Keep the section to commit 8929bc72a1,
this is, as it was before #2374 and #2385 (and how it is still described
in the readme), which has been working fine for years:

> The information in Section Z looks like this:
>
> `10% ☰ 10/100 ln : 20`

instead of reversing the symbols, adding extra characters and completely
botching spacing trying to fix the resulting rendering problems.

No reason to fix what's not broken.

Keep the added 'colnr' configuration, which was a good addition.

autoload/airline/init.vim

@@ -86,16 +86,13 @@ function! airline#init#bootstrap()
     call s:check_defined('g:airline_left_alt_sep', "\ue0b1")  " 
     call s:check_defined('g:airline_right_sep', "\ue0b2")     " 
     call s:check_defined('g:airline_right_alt_sep', "\ue0b3") " 
-    " ro=, ws=☲, lnr=, mlnr=☰, colnr=, br=, nx=Ɇ, crypt=🔒, dirty=⚡
+    " ro=, ws=☲, lnr=☰, mlnr=, colnr=:, br=, nx=Ɇ, crypt=🔒, dirty=⚡
-    "  Note: For powerline, we add an extra space after maxlinenr symbol,
-    "  because it is usually setup as a ligature in most powerline patched
-    "  fonts. It can be over-ridden by configuring a custom maxlinenr
     call extend(g:airline_symbols, {
           \ 'readonly': "\ue0a2",
           \ 'whitespace': "\u2632",
-          \ 'maxlinenr': "\u2630 ",
+          \ 'linenr': "\u2630 ",
-          \ 'linenr': " \ue0a1:",
+          \ 'maxlinenr': " \ue0a1",
-          \ 'colnr': " \ue0a3:",
+          \ 'colnr': ":",
           \ 'branch': "\ue0a0",
           \ 'notexists': "\u0246",
           \ 'dirty': "\u26a1",
@@ -107,13 +104,13 @@ function! airline#init#bootstrap()
     call s:check_defined('g:airline_left_alt_sep', "")
     call s:check_defined('g:airline_right_sep', "")
     call s:check_defined('g:airline_right_alt_sep', "")
-    " ro=⊝, ws=☲, lnr=㏑, mlnr=☰, colnr=℅, br=ᚠ, nx=Ɇ, crypt=🔒
+    " ro=⊝, ws=☲, lnr=☰, mlnr=㏑, colnr=:, br=ᚠ, nx=Ɇ, crypt=🔒
     call extend(g:airline_symbols, {
           \ 'readonly': "\u229D",
           \ 'whitespace': "\u2632",
-          \ 'maxlinenr': "\u2630",
+          \ 'linenr': "\u2630 ",
-          \ 'linenr': " \u33d1:",
+          \ 'maxlinenr': " \u33D1",
-          \ 'colnr': " \u2105:",
+          \ 'colnr': ":",
           \ 'branch': "\u16A0",
           \ 'notexists': "\u0246",
           \ 'crypt': nr2char(0x1F512),
@@ -128,9 +125,9 @@ function! airline#init#bootstrap()
     call extend(g:airline_symbols, {
           \ 'readonly': 'RO',
           \ 'whitespace': '!',
-          \ 'linenr': ' ln:',
+          \ 'linenr': 'ln ',
           \ 'maxlinenr': ' ',
-          \ 'colnr': ' cn:',
+          \ 'colnr': ':',
           \ 'branch': '',
           \ 'notexists': '?',
           \ 'crypt': 'cr',
@@ -236,9 +233,9 @@ function! airline#init#sections()
   endif
   if !exists('g:airline_section_z')
     if airline#util#winwidth() > 79
-      let g:airline_section_z = airline#section#create(['windowswap', 'obsession', '%p%%', 'linenr', 'maxlinenr', 'colnr'])
+      let g:airline_section_z = airline#section#create(['windowswap', 'obsession', '%p%%'.spc, 'linenr', 'maxlinenr', 'colnr'])
     else
-      let g:airline_section_z = airline#section#create(['%p%%', 'linenr', 'colnr'])
+      let g:airline_section_z = airline#section#create(['%p%%'.spc, 'linenr', 'colnr'])
     endif
   endif
   if !exists('g:airline_section_error')

doc/airline.txt

@@ -71,14 +71,12 @@ section  meaning (example)~
          optionally may contain Byte Order Mark `[BOM]` and missing end of last
          line `[!EOL]`
   Z      current position in the file
-           percentage % ln: current line/number of lines ☰ cn: column
+           percentage % ☰ current line/number of lines ln : column
-           So this: 10% ln:10/100☰ cn:20
+           So this: 10% ☰ 10/100 ln : 20   means: >
-	   means: >
               10%     - 10 percent
-	      ln:     - line number is
+              ☰ 10    - current line 10
-              10/100☰ - 10 of 100 total lines
+              /100 ln - of 100 lines
-	      cn:     - column number is
+              : 20    - current column 20
-              20      - 20
 <
   [...]  additional sections (warning/errors/statistics)
          from external plugins (e.g. YCM/syntastic/...)
@@ -345,16 +343,6 @@ CUSTOMIZATION                                        *airline-customization*
 The following are some unicode symbols for customizing the left/right
 separators, as well as the powerline font glyphs.
 
-Note: Some additional characters like spaces and colons may be included in the
-default. Including them within the symbol definitions rather than outside of
-them allows you to eliminate or otherwise alter them.
-
-Note: Be aware that some of these glyphs are defined as ligatures, so they may
-show up different (usually bigger) if followed by a space. This only happens
-if both the font and terminal implementation used support ligatures. If you
-want to follow a glyph with a space _without_ the alternate ligature being
-rendered, follow it with a non-breaking-space character.
-
 Note: You must define the dictionary first before setting values. Also, it's
 a good idea to check whether it exists as to avoid accidentally overwriting
 its contents. >
@@ -367,12 +355,12 @@ its contents. >
   let g:airline_left_sep = '▶'
   let g:airline_right_sep = '«'
   let g:airline_right_sep = '◀'
-  let g:airline_symbols.colnr = ' ㏇:'
+  let g:airline_symbols.colnr = '㏇'
-  let g:airline_symbols.colnr = ' ℅:'
+  let g:airline_symbols.colnr = '℅'
   let g:airline_symbols.crypt = '🔒'
   let g:airline_symbols.linenr = '☰'
-  let g:airline_symbols.linenr = ' ␊:'
+  let g:airline_symbols.linenr = '␊'
-  let g:airline_symbols.linenr = ' ␤:'
+  let g:airline_symbols.linenr = '␤'
   let g:airline_symbols.linenr = '¶'
   let g:airline_symbols.maxlinenr = ''
   let g:airline_symbols.maxlinenr = '㏑'
@@ -392,8 +380,8 @@ its contents. >
   let g:airline_symbols.branch = ''
   let g:airline_symbols.colnr = ':'
   let g:airline_symbols.readonly = ''
-  let g:airline_symbols.linenr = ' :'
+  let g:airline_symbols.linenr = '☰'
-  let g:airline_symbols.maxlinenr = '☰ '
+  let g:airline_symbols.maxlinenr = ''
   let g:airline_symbols.dirty='⚡'
 
   " old vim-powerline symbols