2.0.0-alpha2

This is the second alpha release of our "dev builds", focusing on Quake 2 support.

Quake mappers will probably want to stick to the previous v0.18.2-rc1 release.

Fixes since alpha1:

• fix blown out lightmaps with bounce and lightstyles (2e0e236)
• fix lightstyles being deleted if the map leaks (9d7f83a)
• fix surface lights not illuminating the back faces of lit water (b71a4eb)

Additions since alpha1:

• _light_twosided 1 bmodel key for enabling two-sided surfaces to receive light from either direction, mostly for Q2 opaque lit water. We might enable this implicitly on Q2 warp surfaces in the future, as we currently do on Q1 lit (opaque) water. (b893e67)
• _tex_saturation_boost 1 worldspawn key (light) for boosting texture saturation in bounce calculations, to emulate vanilla Q2 tools (44dadd8)

Other notes:

• VS runtime for the Windows builds: https://aka.ms/vs/17/release/vc_redist.x64.exe
• Documentation is now at: https://ericw-tools.readthedocs.io