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
don't bind LibGDX-Desktop examples at integration-test phase anymore

This made the examples automatically execute in a "mvn install" call.
This has now been disabled. You can still run the examples manually with
"mvn antrun:run".
Collections.emptyIterator() is 1.7 API but we don't want to give up 1.6

We don't want to give up 1.7 compatibility right now but
Collections.emptyIterator() is Java 1.7 API. For now we've made our own
replacement. If we finally switch over to 1.7 we can use
Collections.emptyIterator() directly.