amberc.js: move start of compilation to AmberC.main()
amberc.js: move handling of commandline parameters to amberc
amberc.js: handle missing parameters in amberc script
amberc.js: create configuration object in amberc script

also export createDefaults() function
amberc.js: add defaults.smalltalk in main() function

if it is added in the createDefaults() function
the user could override it
amberc.js: throw exception if configuration object is invalid
amberc-grunt: adjust to new compiler configuration
Compiler-Exceptions: add RethrowErrorHandler
amberc.js: set RethrowErrorHandler before compilation