Style fixes to BRoster, move docs to doxygen.

Keep the brief description as a regular comment above each public method.

Leave the docs of private methods.

Some variable renaming mostly because of abbreviations.

Add documentation for all the public methods and app_info members and defines
that didn't have docs in the cpp file.
BString docs: Remove extra "to" in AppendChars() string param

Thanks stippi for noticing this oversight.
BString docs: Fix a bunch of other stuff.

A lot of clarification.

Also, sometimes "the object" was used to refer to the BString you're doing
stuff to and sometimes "the BString" was used, settle on "the BString".