remove acorn-recast
yank out acorn-recast and replace it with our own code generator
remove jsx known-tags and use the latest jsx known tag definition
modify regex object instead of creating a new literal
fix indentation
update jsx empty test to new dom tags behaviour
add back regex.flags in unicode regex transformer
run 6to5-node repl in a context
change acorn-ast-types to internal builders
remove useless traverse.Delete
better eval contexts in bin/6to5-node
move some util and traverse methods into types
fix linting errors
Merge branch 'master' into code-generator

Conflicts:
	package.json
remove unused variables
add generation completeness test
update traverse visitor keys to acorn ones
expose traverse.VISITOR_KEYS
remove invalid node types from generator and add todo ones
add blacklist syntax feature checking to 6to5/register