add AirlineRefresh command.

doc/airline.txt

@@ -136,7 +136,10 @@ COMMANDS                                                  *airline-commands*
   Toggles whitespace detection.
 
 :AirlineToggle                                              *:AirlineToggle*
-  Toggles between the standard 'statusline'
+  Toggles between the standard 'statusline' and airline.
+
+:AirlineRefresh                                            *:AirlineRefresh*
+  Refreshes all highlight groups.
 
 ==============================================================================
 CUSTOMIZATION                                        *airline-customization*

plugin/airline.vim

@@ -98,6 +98,7 @@ endfunction
 command! -nargs=? -complete=customlist,<sid>get_airline_themes AirlineTheme call <sid>airline_theme(<f-args>)
 command! AirlineToggleWhitespace call airline#extensions#whitespace#toggle()
 command! AirlineToggle call <sid>airline_toggle()
+command! AirlineRefresh call airline#load_theme()
 
 call <sid>airline_toggle()
 

t/commands.vim

@@ -25,5 +25,9 @@ describe 'commands'
     execute 'AirlineTheme dark'
     Expect g:airline_theme == 'dark'
   end
+
+  it 'should have a refresh command'
+    Expect exists(':AirlineRefresh') to_be_true
+  end
 end