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.
QF currently uses unique file names for screenshots and server-side
demos (and remote snapshots), but they're generally useful.
QFS_NextFilename has been filling this role, but it is highly insecure
in its current implementation. This is the first step to taking care of
that.
This reduces the overhead needed to manage the memory blocks as the
blocks are guaranteed to be page-aligned. Also, the superblock is now
alllocated from within one of the memory blocks it manages. While this
does slightly reduce the available cachelines within the first block (by
one or two depending on 32 vs 64 bit pointers), it removes the need for
an extra memory allocation (probably via malloc) for the superblock.
The uptime display had not been updated for the offset Sys_DoubleTime,
so add Sys_DoubleTimeBase to make it easy to use Sys_DoubleTime as
uptime.
Line up the layout of the client list was not consistent for drop and
qport.
Sys_LongTime returns time in microseconds as a 64-bit int. Sys_DoubleTime
uses Sys_LongTime, converts to double and offsets 0 time by 4G (2**32).
This gives us consistent sub-microsecond precision for a very long time.
See http://randomascii.wordpress.com/2012/02/13/dont-store-that-in-a-float/
