New functions implemented

[Justin Meza]

Just updated the ``future'' branch with new-style functions. It
simplified a lot of the parsing logic because now we can detect where
function arguments end and do not need an additional pass to build up
a function table and pass it around while parsing.

Also, functions are now a basic value type (like NUMBRs, TROOFs, etc.)
which will facilitate the transition to BUKKITs (which can store
functions alongside other values).

The next milestone will be the SRS cast now that 1.3 functions are
implemented (this was the main impediment before).

All building up to BUKKITs, hopefully coming soon.