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
feat(transpiler): constructor and typed field semantics

fixes #11 (constructor and typed field semantics)
fixes #42 (Should we infer class property types from ctor args ?)
fixes #17 (number (js) should map to num (dart))