Doxygen has been warning that `<outp>` and `</outp>` are not valid XML/HTML commands since commit cb6d5d76 on 20016-04-04. That's primarily because there is at present no way to tell Doxygen to recognize new XML/HTML tags. The actual errors look like this:
```
.../string.doxygen:187: warning: Unsupported xml/html tag </outp> found
```
I hate build errors since they a) cause needless concern, and b) make it harder to notice when I've introduced a new error. So switch from XML/C## style markup to Doxygen style markup for the "outp" annotation.
Closes#2699
Fixes issues with:
* 'string' function synopsis
* Redirection display issues
* Better file & path detection
* Rendering of % & @ chars in both html and man
* @ symbol in tutorial
Improves robustness by implementing an @EOL marker to prevent hold buffer dumping extra chars after the end of an expression.
Added new '{{' and '}}' meta-chars for when you want curly braces in a regexp that was previously tripping up the lexicon.
Improve man/html presentation consistency for
* string
* printf
* prompt_pwd
* type
Use cli-styling for 'practical' examples.
Add <bs> tag for presenting content with preceding backslash.
Signed-off-by: Mark Griffiths <mark@thebespokepixel.com>
