After !2853, the statement that the "longest file extension is
always considered" is no longer true. Both NAME_WLE and
LAST_EXT now return details based on the shortest file
extension.
Fixes: 7a25ef326b (Help: Add documentation for new get_filename_component components, 2019-01-24, 3.14.0-rc1)
Revise docs for all "Scripting Commands", except four find_XXX
that use a macro suite of their own.
* Take full advantage of the improved syntax highlighting.
* Make consequential use of <..> placeholders.
* Clarify things here and there in the text.
Specific improvements to some command docs:
* "math": Correct description of novel hexadecimal capability.
* "if", "foreach", "while": Provide link to "endif" etc
* "foreach", "while": Mention "break" and "continue".
* "foreach": Simplify explanation of ``RANGE`` and ``IN`` signatures;
advise against negative arguments or reverse ranges (compare issue #18461)
* "endif", "endfunction" etc: Explain that the argument is optional and
maintained for compatibility only
In the get_filename_component command, add a new BASE_DIR parameter to
use with the ABSOLUTE and REALPATH options. This will be used when
finding an absolute path from a relative path.
