amberc: add help output for the '-D' flag
fix for Set >> #add:
Add a favicon

I took the image from amber-lang.net and removed the reflection; then I
used http://www.favicon.cc to generate the favicon.
Merge pull request #518 from kpullen/add-favicon

Add a favicon
Merge pull request #517 from mkroehnert/compiler

amberc: add help output for the '-D' flag
Fixes issue #519
Kernel: add Smalltalk>>#globalJsVariables
SemanticAnalyzer: use #globalJsVariabls in #errorUnknownVariable: method
Smalltalk: methods for adding/removing global JS variables
amberc.js: add js globals support
grunt-amberc.js: add support for JS globals
amberc: add support for JS globals
amber-cli: recompile
Update API-CHANGES.txt

add Smalltalk>>addGlobalJsVariable: and Smalltalk>>deleteGlobalJsVariable:
Kernel-Objects: remove '^self' from #add/#deleteGlobalJsVariable methods
Merge pull request #523 from mkroehnert/compiler

Add support for managing JS global variables needed by the compiler
Enhanced Amber REPL.
save previous results; Ctrl+L to clear screen
DRYed; also: assign new variables only if necessary
refactored too long repl methods