HGBase Code (Desktop)

Code format improvements.

Download a new version to an update directory.
Check on startup if a new version may be installed.

Updater application for updating HGBase applications.

Correction of typos and docs.
Formatting.

Cache images for a given file name to read an image only once.

Extend functionality (used by tjger).

Add getAction method to menu.

Register actions instead of overriding onAction method.

Allows to register menu actions instead of overwritting onAction method.

Code format improvements.