DIFFERENCES TO MAIN APIs/UNSUSPECTED BEHAVIOUR
[GWTGL20]
- unfixable: client side arrays (vertex arrays) are unsupported. VertexArray and IndexArray class simulate VAs via
  VBOs so SpriteBatch etc. still work as intended.
- getters are not implemented, some are not supported by WebGL
- uniform location id allocation returns multiple ids if one queries for one uniform multiple times. Not an issue as long
  as you don't start comparing those ids to each other.

[GwtInput]
- mapping of a couple of (minor) keys is bad, see FIXMEs

[GwtFileHandle]
- only internal and defined classpath files are supported.
- if you try to access an audio file or an image file via FileHandle#read() and other such methods,
you won't get anything sensible.
- binary files specified in the assets.txt file can be opened but are slow to read, avoid if possible.

[Reflection]
- Reflection is available for defined classes. Please see http://code.google.com/p/libgdx/wiki/Reflection 

DIFFERENCES IN EMULATION
[BufferUtils emu]
- BufferUtils#newLongBuffer() works but will not return a direct buffer. Since we don't pass long
  buffers to OpenGL ES we should be fine.
  
[Texture emu]
- all textures are RGBA8888, i have yet to find a way to get proper pixel formats working.
  
[Pixmap emu]
- All Pixmaps have RGBA8888 as the internal format, i have yet to find a way to fix that. Doesn't seem
feasible due to the use of Canvas.
- This is highly experimental and hacked. Pixmap#getPixels() returns an IntBuffer that contains a single
  integer. You can not read pixel data with this method!
- Colors returned by Pixmap#getPixel() may slightly deviate from the original colors on some browsers on
  MacOSX due to the use of ImageIO which modifies colors while decoding PNGs...
- everything else should work as intended, some things might deviate from the usual behaviour a bit.

[NumberUtils emu]
- double to long, long to double methods return 0.

[InputStreamReader emu]
- assumes encoding is UTF-8, always.

[System emu]
- ripped from GWT with additions by jgw.
- Excluded explicitely in .classpath of gdx-backends-gwt!
- Excluded from ant build (build-template.xml)!

[Unsupported Classes]
GdxBuild.java
GdxNativesLoader.java
SharedLibraryLoader.java
Gdx2DPixmap.java
PixmapIO.java
ETC1.java
ETC1TextureData.java
KTXTextureData.java
ScreenUtils.java
RemoteInput.java
RemoteSender.java
AtomicQueue.java
LittleEndianInputStream.java
PauseableThread.java