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.
GL still has its own functions for enabling and disabling fog while
rendering, but GLSL doesn't need such (thanks to the shaders), nor will
vulkan (and the software renderers don't support fog).
As qwaq doesn't yet do any 3d rendering, it doesn't use efrags and thus
wasn't pulling in the object file, but the various renderers were trying
to access it. And I thought plugin builds were more difficult (I had
forgotten).
This fixes the segfault and pushes things very much in the desired
direction of proper system independence for rendering and presentation
separation (though things were headed in the right direction before).
This fixes the status bar refresh issues in sw. The problem was that with
two viddef's hanging around, things got a little confused and recalc_refdef
wasn't getting into the renderer.
This allows the vid module to load the render module and access render
specific functions before the renderer initializes, which happens to need
an initialized vid module...
The renderer now gets initialized and things sort of work (qw-client will
idle, though nothing is displayed). However, as the viddef stuff is broken,
it segs on trying to run the overkill demo.
