loader: refactorings

Less `window` and `smalltalk` global usage.
Using global `amber` as a communication channel for load/init.
Moved toggleAmberIDE into smalltalk and calling it.
createPackage exported with one parameter only

both `.st` as well as `{.deploy.js,.js}`.
createPackage: with only one parameter at the beginning of .st

Recompile will fix `.js` files as well
(the existing parameter in `.js` does not make any harm,
but should be removed, eventually).
Changelog update
Make new `Compiler.st` for Makefile.

(not sure that it's needed, but it had wrong exporter,
so it is generated from fresh code)
changelog update for 0.10
Merge pull request #391 from herby/gh-384

Fixes #384
Merge pull request #374 from herby/loader-cleanup

loader: refactorings
TabManager class >> toggleAmberIDE rewrite in Smalltalk
No more need for `showdown.js` in amber core.