Add a 1 channel jpg texture test.

This passes on Chrome and Firefox but generates an incorrect
`INVALID_VALUE` error on Safari
Merge pull request #457 from greggman/add-1-channel-jpg

Add a 1 channel jpg texture test.
Fix up WEBGL_debug_shaders test.

getTranslatedShaderSource() should return "" instead of null on failure.
Fixed JS error where newTranslatedSource was not forward-declared.
Merge pull request #458 from jdashg/debug_shaders

Fix up WEBGL_debug_shaders test.
Clarify that conformance test 'version'.

Switched out 'Version <version>' with 'Subset: Version <version>' to
clarify that it only changes the subset of tests, not the actual versions
of the tests run.
Merge pull request #460 from jdashg/version-reword

Clarify that conformance test 'version'.
Add link to previous conf test dir.
Merge pull request #461 from jdashg/version-reword

Add link to previous conf test dir.
Add a test for texture2DProjLod.
Merge pull request #456 from c0d1f1ed/texture2DProjLod

Add a test for texture2DProjLod.
related to pull request #451: added needed check also for versions 1.0.1 and 1.0.2
Expand float texture extension tests to test rendering to RGB textures

Also fix incorrect alpha values in the expected values in the test and
some minor things in presenting test results.
Merge pull request #463 from imzet/utils-vbo-use-prev-versions

related to pull request #451: added needed check also for versions 1.0.1...
Merge pull request #464 from NVIDIA/expand-oes-texture-float-test

Expand float texture extension tests to test rendering to RGB textures