Add more binary operations
Clarify parts of the design
Merge branch 'master' of https://github.com/dominichamon/hup
Adding scope delimiters and expression lists to func, for, if.

Also, else is now optional.
Register native methods automatically and remove native keyword
Allow debug code to be emitted
Mutable variables and scope push/pop
Better handling of named values, better error messages, example input
Merged from upstream