OpenGL/Color: add constant "TYPE"
OpenGL/Shaders: make "color" a shader attribute

Allows using glBindAttribLocation().  Also allows color gradients.
OpenGL/Color: add class ScopeColorPointer

Prepare for GLES 2.0 support.
OpenGL/Color: enable ScopeColorPointer on GLES 2.0

Use glVertexAttribPointer() instead of glColorPointer().
Form/Form: enable shadow on GLES 2.0
TopographyFileRenderer: activate the solid_shader
TopographyFileRenderer: restore the ModelView matrix
OLCTriangle: skip small ranges
OLCTriangle: fix relaxing of closing pairs

Don't decrease a possible end point. Has the side effect of faster
computation in some cases.