Added JSR-305 implementation to dependencies
Cleaned code of Element effect cache class

 - Placed JSR-305 annotations
 - Improved performance using EnumMap instead of HashTable
   (smaller memory size, faster access time)
 - Applied default values properly
Cleaned resource loader implementations

- Added JSR-305 annotations
- Improved exception handling
Cleaned up the time interpolators

 - Added JSR-305 annotations
 - Handled possible runtime exceptions properly
Cleaned up the pulsators

 - Added JSR-305 annotations
 - Handled possible runtime exceptions properly
Refactored ObjectPool

 - Added JSR-305 annotations
 - Removed pooling of small objects
 - Changed pool to soft reference pool
Applied JSR-305 to Niftys SPI
Full refactoring of Nifty

 - Applied JSR-305 annotations
 - Fixed potential null problems
 - Got rid of most Null-Objects
 - Implemented enum related storage system
   -> Mainly used for EffectEventId related storages
 - Got rid of Hashtables
 - Added early checks for problems
 - Added a lot of additional log warnings
 - Formatted code to meet Nifty specifications
 - Implemented proper use of XmlPullParserFactory
 - Fixed ID bug
Cleanup of NiftyStopWatch

 - Slightly improved performance by using a not synchronized collection
 - Avoided creation of log message in case logging is disabled
 - Avoided object creation to receive timestamp
Cleanup element class and layouter test

 - avoid nullity warning
 - improved output of layout test
Fixed screen handling in element class
Fixed initialization order of list box control
Merge remote-tracking branch 'GitHub-void/1.4' into 1.4
Fixed fetching minimal size for scrollbar handle
Added missing JSR-305 annotations to screen controller

Also added the annotations to the implementing interfaces
Set libGDX dependencies to use release version
Improved SizeValue implementation

 - Creation of size values instances don't require String parsing
   anymore in most cases
 - SizeValueType added to bundle the type related data
 - Improved test coverage
 - Fixed wildcard computed value implementation
 - Added proper separation of fixed and computed values
Merge pull request #178 from mkaring/1.4

Refactoring Nifty 1.4