Fixes for the latest SDK version (1.12) and greater API support

* Fixed bug where second handler fired constantly
* Added support for text layer updating
* Added support for getting window background layer
Added support for center and right aligned text
Fixes to window painting
Implemented most of the AppMessage/Dict functions
Updated README.md with latest SDK number and slightly modified instructions
More work on AppMessage + JS integration work
Dictionary functions now appear to be working correctly
Most dict/app message functions working, except for ints

See: https://github.com/kripken/emscripten/issues/1602
Added --typed-arrays 0 to emscripten command

This fixes the issue with flexible structs
First stab at resource support.