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
minimap: initial support
minimap: tidy the transform code a bit, background color and zone dependent scaling
renderers: add ScissorSet and ScissorEnable

Used to control temporarily glScissor, the scissor is also modified
by other parts of the renderer.
Adapted from a commit from `Ishq (ded55d8f12e03aceff) + fixes
cgame: Add scissoring support
minimap: use scissoring to keep the map in the canvas
minimap: add DrawMinimapObject, rework transform and add player arrow
minimap: show teammates, first version
minimap: use the center of the image bounds as it's 3d origin
minimap: add cg_drawMinimap, globalScale and bgColor alpha
Clean up pubkey handling.
Don't build with GLSL optimisation enabled.