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
Documentation added by commit 4b35dab891 (Help: Document how escape
sequences work in a regex, 2018-07-18) is only correct for backslashes
inside `[]` groups. The regex engine does interpret `\` escapes
elsewhere. Fix the docs.
Inspired-by: R2RT <artur.ryt@gmail.com>
Fixes: #18428
Summarize the command signatures in one block at the top of the
documentation as is typical in Unix command-line tool manuals.
Make the mode keywords links to the corresponding full signature
and documentation.
Issue: #17948
Spell out the supported algorithms in a definition list in the
`string(<HASH>)` command documentation. Revise the `file(<HASH>)`
command and CPack module documentation to reference it instead of
duplicating the list.
The new `%s` format specifier is substituted by file()/string()
`TIMESTAMP` sub-commands with the number of seconds since unix-epoch
(1970-01-01 00:00:00 UTC).
Co-Author: Nils Gladitz <nilsgladitz@gmail.com>
string SUBSTRING command now ignores length if it points
past end of string and uses end of string instead.
String SUBSTRING tests now cover more corner cases.
Add a string(CONCAT) command to simply concatenate input arguments
together. This will be useful for combining strings from different
quoting syntaxes. Add a RunCMake.string test covering these cases.
