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.
It seems clang defaults to unsigned for enums. Interestingly, gcc was ok
with the checks being either way. I guess gcc treats enums that *can* be
unsigned as DWIM.
It turns out cam_controls is for pointing the player model in the
direction of movement rather than controlling the camera (I should add
proper camera controls).
Handling of view angles is a little hacky at the moment, but this gets
the chase camera code and most of the common input code into one place,
which will make cleaning up the camera code much easier.
Id's binding of escape to togglemenu interfered with the hard-coding
(want escape to togglemenu (or console as a fallback) no matter what).
This idea was part of mercury's original design, too.
This allows id1/qw config files, and to a certain extent scripts, to
work with the new binding system. It does highlight just how limited the
original system was (many keys could not bound).
Mouse axis input does not work yet as that needs a little more work to
support +strafe and +mlook.
