Fixed "from" import syntax highlighting.
Marked up TODO items.
Constructor and destructor are now highlighted in function face, not built-in.
cast(sometype, somevar) syntax now highlights sometype in a type face.
{ } braces are now highlighted properly.
Highlight duck as a normal type, not as a special built-in.
Improved string interpolation a bit. Needs some good testing to be
sure.
Added more boo macros and the "then:" syntax.