Math: fixed two typos in the test.

They resulted in fact that the test case didn't actually test anything.
Spotted by Clang.
Shaders: minor tweaks.

Non-matching number of opening and closing braces confused editors with
code folding feature.
Shaders: set default values for VertexColorShader uniforms.

Default value for matrix uniform would be zero uniform which would cause
"black screen of death".