Pause main loop while draw event requested

Interaction between main loop iterations and window update events
might be the reason for the glitchy performance on low-spec machines:
the main loop was ticking away at maximum speed even though the
window was stuck in a draw/vsync.

Now the main loop timer is explicitly stopped before a draw request
is submitted, and the loop is only resumed after the draw has been
completed.
Fixed: Compiler warnings about unused variables/code
LegacyCore: Force loop resuming after pop

When returning to an earlier loop context, make sure the loop continues
running again. For example, when returning from busy mode.
Debug|Fixed: Compiler warning about unused code
Fixed|Mac OS X: Mouse input in OS X 10.4

No suppression interval must be used or otherwise the mouse movement will
stop for 250 ms when warping the cursor back to the center.

Another way would be to disassocate the mouse position from the cursor
and handle the native Mac mouse events to get the deltas.
Input: Re-enabled mouse filtering (cvar "input-mouse-filter")

By default mouse filtering is disabled.
All Games: Menu should not be activated by the Shift key

Otherwise Shift-Esc will be difficult to use in the main menu screen,
as Shift will activate the menu and expire the key due to the binding
context change.
Log appropriate DEBUG messages upon input device reset
Win32|Fixed: Alt DDKEY not released when using alt+tab to switch tasks

On Windows the alt key-up event is eaten by the OS when using alt+tab
to switch tasks, prior to our Qt based event handler getting a chance
to process it.

This means it is necessary to monitor QEvent::ActivationChange events
in CanvasWindow and then manually submit a key-up event in response.

We must also track the is-down state of the alt key manually. Although
this is already implemented in the input module, this is too far away
for us to ignore repeat up events (due to cycling tasks and the manual
alt key-up submital).

I was unsure how well the input layer handles repeat state set events
so an additional state has been added to Canvas.

Todo for later: Check whether repeat key-up events are OK and if so,
remove the additional is-down state tracking in Canvas.
Merge branch 'master' of ssh://deng.git.sourceforge.net/gitroot/deng/deng
Input|Fixed: Clear the key repeaters when reseting the keyboard device

Not clearing the key repeaters when reseting the keyboard device
was the cause of the strange/stuck alt key behavior on Windows.
Despite focus being lost the repeaters would continue generating
events, resulting in the DDKEY_RALT state being set to is-down.
Fixed: rend-dev-input-key-state used ASCII char 42 (not DDKEY_MULTIPLY)
Input|Fixed: Apply the DDKEY_MULTIPLY mapping in DD_ModKey()
Win32|Fixed: Install all fonts we might require during startup

We cannot presently load these from doomsday.pk3 they must exist as
native files on the host system.
Added: "global" context for bindings that are globally active

Bindings in the "global" context are always in effect. Moved the fullscreen
toggle and releasemouse bindings to the engine's default bindings.

Todo for later: Remove/relocate the special case handlers in dispatchEvents()
so that the bindings system actually gets all the events first.
Hexen|Fixed: Disallow warp cheat when the player is dead

Warping while dead would turn the player into an undead zombie.
Console: Temporarily hardcoded F11 functionality while console open

Because the bindings subsystem is not accessible when the console
is open, the F11 is now hardcoded to togglefullscreen/releasemouse
when the console is open.

Todo for later: Revert this when the bindings subsystem gets all events first.
Fixed: Fatal error loading a map with a missing/unknown plane material
Map Renderer: Flip the "missing" material on ceiling planes

Always flip the missing material when used on ceiling planes so that
the embedded "missing" text appears correct.
Fixed: Trying to a mobj out of an invalid client info instance

Encountered during a Heretic MP test. The reason why this was called for
an invalid clmoinfo_t is unclear.