Improved error handling
Return correct element from generation
Updates to the build for latest API
Revamping the build system

Revamping the build system to reliably run by deterministically doing
its own layer creation for stylesheets
Merge remote-tracking branch 'stdavis/master'
Support errors without a stack
Properly pass the instance as `this` in function calls, and cleanup of collections
Updates to the todo mvc example
Fix infix operator assignment
Fix parsing of url()s in imports and other calls, refs #33
Ensure directories are created when writing target stylesheets
refs #33
Fix text access when creating new target stylesheets, refs #33
Update page.js for latest API and remove invalid dependencies, fixes #34
tighten up cleanup and element targeting
Apply cleanup at appropriate time
Stricter undefined test
Handle rule and element combinations and fix property inheritance
Don't apply a forElement object as a CSS property value