Add throwSyntaxError support.
build
correcting matching inside delimiters fixes #85

A single pattern var no longer matches multiple tokens inside a delimiter
build
matching too much in group fixes #113
build
Add comments to read tree.
Rewrite syntaxFromToken to use constructor/prototype for performance.
persisting leadingComments on the macro name
build
Merge branch 'perf' of https://github.com/natefaubion/sweet.js into natefaubion-perf
update enforest test since read now just returns directly
build
Merge branch 'natefaubion-perf'
build
threading an expander context object

Using an expander context object throughout the expander instead of
passing individual parameters. Allows easier extension (especially
across macro transformer calls).
threading context into macro transformer
adding mark to expander context
build
using context mark in syntaxCase