Changes

Bug 1125: Unit test to validate that Thread.interrupt() does not disturb
continued rendering of AWT and GLCanvas

Bug 1233 - Add missing range- and pbo-bound checks on
glTexture[Sub]Image[123]D*
Adding missing range- and pbo-bound checks for:
- glTextureImage1DEXT
- glTextureImage2DEXT
- glTextureImage3DEXT
- glTextureSubImage1D
- glTextureSubImage1DEXT
- glTextureSubImage2D
- glTextureSubImage2DEXT
- glTextureSubImage3D
- glTextureSubImage3DEXT

Bug 1234 - GLReadBufferUtil.readPixelsImpl(..) not using [xy] offset in
readTexture.updateSubImage(..)
The passed inX and inY x/y offset for readPixel -> [textureData] buffer, 
must be passed to readTexture.updateSubImage(..)'s destination offset.
I.e. the buffer's content starting at beginning is filled via
glReadPixels w/ offset applied.
Hence the texture update must pass the offset as the destination offset, 
i.e. to be used for glTexSubImage2D's offset.