Update changelog; release.
Improve R_AddNormals

New code results in a more accurate image because 128 / 255 and 127 / 255 do not exactly equal 0.5. There are also fewer and less expensive calculations so it should be faster.
The map thunder spent a significant amount of time in R_AddNormals when loading.
Remove useless rgb max calculations in R_UploadImage
renderer: ignore a few shader keywords only relevant at map generation time.

These keywords were causing some shaders to be skipped, causing the ‘missing
texture’ texture to be displayed.
fix potential buffer overflow for openal sfxHandle_t registrations
Changelog update.
Make it easier to launch Unvanquished via gdb.
Merge tag 'v0.15.0' into debian; update debian/changelog.

Release

Conflicts:
	src/engine/client/snd_openal.c
Merge branch 'master' into debian
Add more checks for invalid bts when parsing
Print behavior tree parse errors by default
Check if child node of condition was read
Separate behavior tree parsing and execution
Merge remote-tracking branch 'remotes/origin/master' into bots
librenderer: do not warn on 'deformMagnitude'
Rewrite action nodes

Now there is better parameter checking, and it is easier to add new action nodes
Remove unnecessary indirection
Add BotActionRoamInRadius

allows the bot to roam within a specified radius of a specified target
Make camper bots use action roamInRadius
Make camper aliens evolve