Convolution Mustpass Test
David Blythe, SGI (blythe@engr.sgi.com)

Test 3x3 kernels:

    1/9 1/9 1/9		0   -1	 0
    1/9 1/9 1/9        -1    4	-1
    1/9 1/9 1/9		0   -1	 0

0) Test illegal parameters on filter loads.

1) Create 3x3 kernel, RGBA, FLOAT.
    Load and readback using GetConvolutionFilter
    Compare that they are equal within resolution returned by queries

2) DrawPixels with 6x6 image and Convolution2D enabled. Disable
    convolution, readback and compare results.

3) Test ConvolutionFilter scale & bias on filter load.

4) Test PostConvolution scale & bias using 6x6 image and DrawPixels.

5) Test Convolution on ReadPixels.

6) Test Convolution on CopyPixels and TexImage2D.

7) Test CopyConvolutionFilter using DrawPixels to test convolution result.

8) Test SeparableFilter2D as above, except CopyConvolutionFilter

9) Test Convolution1D as above.