Simplified MBDataHandlers

- Removed MBDataHandler protocol
- Renamed MBDataHandlerBase to MBDataHandler
- Implemented caching functionality in MBDataHandler, so any subclass can use caching by setting enableCaching=YES
- Caching can be turned on and off and be parameterized for individual documents by overriding cachingParametersForDocument
- The only method you are required to override is doLoadDocument:withArguments
- storeDocument and cachingParametersForDocument can be optionally overwritten
Fixed a memory leak
Improved warning visibility in console by adding a warning sign emoji before each warning, to better distinguish them from regular debug messages
Updated framework header and project
Merge branch 'feature/mbdatahandler-simplification' into develop
Merge branch 'feature/mbproperties-memory-leak-fix' into develop
Merge branch 'feature/improved-warning-visibility-in-console' into develop