Debug|libgui|GLState: Verifying parts of the GL state
libgui: Window state management behavior improvements

Fixes the Windows-only problem where a fullscreen window would
randomly use the previous display resolution as its size after a mode
change.

IssueID #1892
Merge branch 'master' of https://github.com/skyjake/Doomsday-Engine
libgui|Unix|OS X: Typo
Fixed|Client|Windows: Potential crash if closing window during startup

When game resources are being located, games become current for short
periods of time (kludge in Games::locateStartupResources()). If a
"quit" command happened to be executed at this time, a crash could
occur in the console command execution, presumably if the game suddenly
was removed in another thread.

As a workaround, closing the window is disallowed during busy mode.

IssueID #1895
Fixed|UI|Updater: Don't recheck if settings weren't changed

In the update notification dialog, if one opens the Updater settings
and closes it without changing anything, a recheck of available
updates is unnecessary.

IssueID #1831
Cleanup: Unused function
UI|Task Bar: Added a separate in the Log menu
Console|libdoomsday: Rudimentary access to de::Config variables

This commit introduces a simple mechanism that allows the user to
interactively access de::Config variables as if they were traditional
cvars. The allowed operations are checking the value of the variable
(having it printed in the console), or setting the value (number or
text only).

This is not a long term solution, though. When the console is based on
Doomsday Script, this mechanism should become unnecessary and obsolete.
(Although some form of mapping between traditional cvar identifiers and
Config variables is still needed.)
Cleanup
libgui: Querying the ID of a window
Refactor|Client|libappfw|libgui: Replaced 'vid-fsaa' and 'vid-vsync' with Config variables

Console variables are game-specific, however the user most likely
prefers to use the same FSAA/vsync settings for all games as their
appropriate values depend on the available hardware.

Now the FSAA and vsync settings are configured persistently using
Config.window.main.fsaa and Config.window.main.vsync. The old cvars
were removed, however they can still be accessed via the console
command line using a mapping.

IssueID #1832
Fixed|ClientWindow|Windows: Use of the new fsaa/vsync variables
Debug|libgui|GLTarget: Converted a GL assert to a debug message

On Windows, this assert may fail during canvas recreation.

Todo: In the long run, make canvas recreation unnecessary. Hopefully
Qt 5.4 will help here.
Fixed|libdoomsday: Clearing mapped Config variables from database
Merge branch 'master' into common-episode-definition