Change to using glow OpenGL bindings.

gofmt -w -r 'gl.Int -> int32' ./
gofmt -w -r 'gl.Sizei -> int32' ./
gofmt -w -r 'gl.Uint -> uint32' ./
gofmt -w -r 'gl.Double -> float64' ./
gofmt -w -r 'gl.Pointer -> gl.Ptr' ./
gofmt -w -r 'gl.GoStringUb -> gl.GoStr' ./
Focus dev environment on implementing multilevel diff highlighting.
Improve lineDiff highlighter to do inner char diff highlighting.

Avoid having two separate highlighters for left and right sides; merge
into one with two iterators.