Major refactoring to support addon specific translations.

Major refactoring to support addon specific translations.

* Refactored getAvailableAddons and getRunningAddons. Internally addons can be queried by path to facilitate identification of currently calling addon.
* addonHanler.getCodeAddon() retrieves the addon instnace for the calling addon, using stack inspection.
* addonHandler.initTranslation() adds the ettext _ function to the calling module to support addon specific translation (it relies on addonHandler.getCodeAddon internally).
* Many more minor tweaks and corrections.