Editor lexer support for keywords

[takeshimiya]

I've made a lexer for FreeBasic, but in the road I
found that C::B doesn't supports more than one
"Language Keyword".

Currently it supports three Keyword groups: Language,
User, and Documentation.

Scintilla haves 4 Language Keyword groups for Basic, so
the lexer doesn't take in account all the keyword groups.

It would be good if new "Language" or any other Keyword
could be specified from the XML files.
So the groups would be added dinamically, and you could
have more groups than Language, User, and Documentation.

And it could lead to better separation of keywords (ie.
I could separate the C keywords from the C++ keywords).
They could use the same coloring or not, that's up to
the XML lexer.

_{Note: I've submitted also to berlios tracker.}

What do you think?