bugs and performance

Lots of bug and performance fixes. Fast enough to finally self-host!

• Bugs: #78, #77, #74, #67, #61, #69, #73, #71, #74,
• can now concat a macro "module" with sjs --module <module name> #25

v0.1.2

• :expr parse class working #28
• hygiene fixes #15 #17
• allowing macros to override keywords #33
• major refactoring of expander

v0.1.1

• node autoloading, AMD support
• fixes to issues #18, #24, #26, #40