Various fixes to better support doxygen's lexer files

[doxygen]

Thanks for the nice VSCode plugin.

While testing it on Doxygen's lexer files, I ran into a couple of small issues, and decided to dive into the code and try to fix them.

Here is the list of fixes:

• Prevent <,>,{,} characters inside character ranges from breaking the scanner.
• Allow TokenType.Action also in WaitingAction state.
• Allow comments in definition section and condition blocks.
• Allow comments at more places in the syntax highlighting.
• Fix compile issue with undefined in changeValue<E>().

[babyraging]

Hi there, thank you very much for the PR, sorry for the late response.

Code looks good, I'll merge it and push a new version as soon as I get back home.

[doxygen]

@babyraging Any update on when this will be merged?

[babyraging]

@doxygen hi there, sorry for the late response....have been busy IRL...

PR merged and new version has been published, you should now be able to update it.