This is an extremely extensive patch as it hits every cvar, and every
usage of the cvars. Cvars no longer store the value they control,
instead, they use a cexpr value object to reference the value and
specify the value's type (currently, a null type is used for strings).
Non-string cvars are passed through cexpr, allowing expressions in the
cvars' settings. Also, cvars have returned to an enhanced version of the
original (id quake) registration scheme.
As a minor benefit, relevant code having direct access to the
cvar-controlled variables is probably a slight optimization as it
removed a pointer dereference, and the variables can be located for data
locality.
The static cvar descriptors are made private as an additional safety
layer, though there's nothing stopping external modification via
Cvar_FindVar (which is needed for adding listeners).
While not used yet (partly due to working out the design), cvars can
have a validation function.
Registering a cvar allows a primary listener (and its data) to be
specified: it will always be called first when the cvar is modified. The
combination of proper listeners and direct access to the controlled
variable greatly simplifies the more complex cvar interactions as much
less null checking is required, and there's no need for one cvar's
callback to call another's.
nq-x11 is known to work at least well enough for the demos. More testing
will come.
I added Sys_RegisterShutdown years ago and never really did anything
with it: now any system that needs to be shutdown can ensure it gets
shutdown on program exit, and in the correct order (ie, reverse to init
order).
the SDL target files for Despair since he's working on the currently). Also
make progs segfault handling much more robust (and general: sigill etc too:)
the background. This is achieved by doing only a (qf)glFlush at the end of
the frame, doing the inter rendering-frame processing (ie, client frame
processing), glFinish, glXSwapBuffers, then starting the next frame. I've
changed the glFinish call in SCR_UpdateScreen to glFlush and the glFlush
call in GL_EndRendering to glFinish because there's no point in calling
glFinish followed by glFlush. Also, SwapBuffers should always be precedded
by glFinish rather than just glFlush (in Lordhavoc's experience). The
GL_EndRendering at the end of SCR_UpdateScreen got moved to the beginning.
