Area viewer: Added support for shared resources to reduce memory load
Improvements to Area Viewer and BAM decoder

- Added support for active/inactive background animations (both
icon-wise and to real animations)
- Updated BamDecoder
	- Significantly reduces memory consumption of BAM v1 resources
	- Created a common BAM decoder interface for easy extensibility
	- Added separate classes for BAM v1, BAM v2 and a new class for pseudo
BAMs (consisting of custom images)