rename callback function parameter to `amber`

... in comment example at the beginning of file
Fixes #893

- Adds PackageHandler >> commitPackage:onSuccess:onError:
- Adds Environment >> commitPackage:onSuccess:onError:
- Adds PackageCommitError class
- Adds HLPackageCommitErrorHelper to help the user in case the package
- commits fails.
- Improves HLRequestWidget to also work with inputs instead of textareas
Fixes commit path setting when helios runs from within another frame
Fixes #897

Do not handle signaled exceptions twice in Helios (or any other
connected Amber environment).
Fixes HLTabSelectionWidget rendering
Deprecates Object >> try:catch: in favor of BlockClosure >> tryCatch:
amberc: -l libraries not used to construct compiler. Fixes #888
Merge pull request #899 from herby/gh-888

amberc: -l libraries not used to construct compiler. Fixes #888