[Engine] Additional render diagnostics
[Engine-Slick2D] Fixed Sprite offsets
[Engine-libGDX] Fixed offset values of font rendering
[Client] Reduced required object allocations for light calculation
[Engine-libGDX] Using vertex buffer objects to render (slight performance improvement)

This change applies to the sprite batch that is rendering all the graphics. Due to the high amount of texture switches this improves the rendering speed
[Engine-libGDX] Activates texture mipmapping

As all textures that get resized are usually reduced in size, the mip mapping of the textures improves the rendering performance. How ever it takes longer to load the textures and they use more graphic resources.
[Engine-Slick2D] Fixed postprocessing artifacts
[Engine-libGDX] Improved fetching of possible screen resolutions
[Engine-Nifty] Fixed click handling for Nifty-GUI
[Client] Fixed avatar tags
[Client] Improved login dialog look

Vilarion made the login dialog look crappy. Fixed that.
[Client] Change walk-to to double click
[Engine] Added listeners to monitor forwarding state
[Client] Properly reset Nifty mouse input once the forwarding is released
[Client] Allow rendering of entities that were deleted between the update and the render call

This prevents the character from disappearing for a single frame in most cases.
[Client] Fixed possible NPE during skill update
[Engine] Only report real changes of the forwarding handler
[Client] Hide FPS counter
[Client] Added option to show and hide the FPS display
[Engine-libGDX] Fixed listing of valid screen resolutions