Initial support for Forth

Initial support for Forth

This is based on the Scala parser, which is actually quite
incorrect -- assumes existence of single-quote strings (which
will cause problem on any file with symbols), doesn't know
multiline strings, doesn't handle nested comments: all of which
made it a pretty good starting point for Forth.

Parsing Forth is impossible, but this will recognize comments,
strings and blank lines on most projects. Tested against FreeBSD
source.