Change view angle parameterization

Avoid discontinuity for cv when uv goes through 0.5
Add verification for parameterizations
Change parameterization for precomputed transmittance

Use the dimensions height and view angle instead, saving transmission to the end of atmosphere.
Added Octave script for ViewAngleParameterized()
Better detection when near atmosphere
Use vec2 instead of vec3
Sign corrections of precomputed transmittance
Improved debug messages
FetchTransmission angle correction failed to compute correct sign of angle correction
Change SingleScattering and GatheredLight into using vec2