Merge branch 'master' into Glew_Version_For_Real
- fixed some Linux warnings.
- Shut up GCC aggressive optimizer warnings.

From what I can see, GCC would miscompile the involved loops, because the index variable is 'signed int' and the multiplication with an unsigned would cause signed overflow (undefined behavior). Change the index variable type to 'unsigned int' to expect unsigned overflow (conformant to standard).
- use vertex buffer and reuse of data for stencil drawing. A stencil needs to be drawn multiple times with the same polygons so this is a good place to optimize.
Merge branch 'master' into Glew_Version_For_Real
Don't reset the inventory of dead players
- fixed dynamic light definition for Hexen's blue candle.
Merge branch 'master' of https://github.com/rheit/zdoom
Added a check that doesn't print empty obituary strings, as wad's that hide obituary strings in multiplayer games end up spamming a lot of empty lines.
- rewrote sky dome rendering to use a static vertex buffer if not on OpenGL 2.x.
Merge branch 'master' into Glew_Version_For_Real
- use buffer for rendering the sky on all GL versions since the differences for making GL2.0 work are rather small.
- fixed compile error in gl_skydome.cpp
- disable GL_ARB_buffer_storage when a -glversion parameter less than 4.0 is given. According to the spec this extension requires 4.0 so if emulating something lower it should not be used.
- added benchmarking calls for glDrawArrays to see how well issunig draw calls performs on different hardware.
- use a software buffer for immediate mode rendering. This allows using the regular buffer code to collect data for both render modes and allows removal of a lot of duplicated code.
- removed old immediate mode path for generating stencils.
- fixed: Plane height changes only updated the first buffered vertex for the respective plane.
- fixed: GLPortal::DrawPortalStencil must apply the render state before drawing anything.
- convert skybox rendering to use the buffer interface.
- removed gl_usevbo CVAR because with recent code changes it has become useless. If GL_ARB_buffer_storage is present, buffers will always be used.