* Pass the same compiler flags like make.
* Update FindSDL2.
* Remove unneeded FindOggVorbis.
There still some options missing, like the RPATHes or he ability to
define the system wide installation directory.
Make sure that the window is destroyed at gl renderer shutdown and
recreated by the soft renderer. Don't deinitialize SDL in the
softrenderer, that's done by vid.c. And make sure that we start the soft
renderer with a clean GL state.
I've chosen the minimal invasive way for this:
* Import miniz and remove -lz linker flags.
* Create a short header minizconf.h roviding everything we need
originally defined by zconf.h and not provided by miniz.
* Replace zlib.h with miniz.h and minizconf.h.
The input system backend was once used in the client and the renderers,
but for some years now it has been an integral part of the client only.
Move it there.
The last commits did some bigger changes to the interaction between the
GL renderers and the client. The code is now SDL 2.0 conformant, window
and context creation are strictly distinct operations. SDL is only
initialized when necessary. Since this broke the client <-> renderer
API, bump it's version.
There a lot of things left to do for dark and cold winter evenings:
* The software renderer implements it's own window handling and
reinitialized SDL whenever vid_restart is called. This is highly
problematic.
* vid_fullscreen is abused to communicate changes to renderer config
throughout the code. That's a very ugly, messy and potential very
problematic hack. But not easy to remove.
* Some funtion calls between the client and the renderer are
unnecessary.
The changes to the client <-> renderer interaction fixed issue #302.
In the old world we deinitialized and reinitialized SDL each time we
restarted or changed the renderer. That would clear the whole GL state.
In the new world we let SDL running and just recreate the windows. In
some cases parts of the old renderers state would leak into the new
renderer, leading to strange problems.
