#### Brief overview of PR changes/additions
Use a ` +$` search-and-replace to remove trailing spaces in `.cpp` and
`.h` source code files to remove unwanted trailing whitespace that has
crept into a number of files.
#### Motivation for adding to Mudlet
To clean up files as `git` notices such white-space and objects in some
circumstances - and such spaces are redundant in the source code.
#### Other info (issues closed, discussion etc)
Signed-off-by: Stephen Lyons <slysven@virginmedia.com>
<!-- Keep the title short & concise so anyone non-technical can
understand it,
the title appears in PTB changelogs -->
#### Brief overview of PR changes/additions
Parses the style argument of MXP version, like <VERSION StyleID>, and
returns the version (and style id) only when an empty <VERSION> tag is
send. Cf. https://www.zuggsoft.com/zmud/mxp.htm#Version%20Control This
is also how Zmud, Cmud and Mushclient process the <VERSION> tag.
#### Motivation for adding to Mudlet
Enhance MXP v1.0 compliance
#### Other info (issues closed, discussion etc)
cf. [MXP enhancements, was PR
#4200](https://forums.mudlet.org/viewtopic.php?p=47108#p47108)
