chore(README): update instructions
refactor(transpiler): split the monolithic dart transformer

fixes #24

The new architecture conforms with the Traceur architecture.
design: update change_detection
chore: fix karma dart setup
design: add test change_detection
doc(README): HOWTO debug the transpiler
fix(DartWriter): number (js) maps to num (dart)
feat(lexer): initial (wip) implementation.
feat(DartWriter): support string interpolation
feat(facade/lang): support int
refactor(lexer): rename to scanner, use ints, etc.
fixes to get tests green with karma dart
test: add example test for change_detection