SH-2181 Fix for alpha flickering when basic shaders enabled (don't use glAlphaFunc when shaders are available).

Reviewed by Leslie

SH-1990 Fix for redundantly applying some color scaling to sky and water (also add some snazzy specular bloom from the sun)

--HG--
branch : oops

SH-2031 Disable usage of glMapBuffer (again).  Despite using MapBufferRange, this is still a source of frame stalls.

SH-2031 Followup to curl threading work -- don't start and stop the thread on every request, use a signal (cuts time spent in Pump IO down from 1-2 ms to 0.1ms)

Reviewed by Kelly

Reviewed by Leslie