Add new fuzzy background image option.

This commit adds a new cmdline switch -f, which makes a screenshot and
then blurs that image with gaussian blur and then uses it for the
background picture.
Fuzzy option uses background

Fuzzy option now uses COMPOSITE extentsion to grab the background behind
the lock screen and then blurs it and uses for the background image.
OpenGL blur in one direction

Now I have managed to get OpenGL working enough to blur the
image in one direction, now i need to add a second pass.
OpenGL blur implemented

Blur is now implemented but there are no error check or cleanup done.
So after a few frames the memory usage gets enormous.
Add automatic screen redrawing

I used the DAMAGE extentsion to track changes to other windows.
Seperate unlock indicator from screen

Now redrawing the screen does not cause the unlock indicator to be
redrawed.
Bugfix: clear unlock indicator surface

Previous commit reused one surface for drawing the unlock indicator.
However the middle transparent part got darker and darker because the
surface was not cleared before drawing again. Now it is fixed.
Remove some debugging code
Added more output for X11 errors
Eliminated some warnings
Blurring optimized

I increased blur radius but used fever texel lookups.
Handle resize for openGL
Create damage objects for later mapped windows

At init damage objects are created, but if a window is create after
i3lock has initialized, the damage to it was not tracked. Now i3lock
will listen to MapNotify event and tracks damage to those new windows
also.
Do not redraw when screen is off

Use DPMS to check if the screen is off before redrawing.
Add some cleanup code

Did some leak checking with valgrind and removed some obsolete code.
Fix errors with destoyed windows

Xlib errors aborted the program. I switched to using XCB for DAMAGE
extension. And then ignored the error messages for DAMAGE extension,
which are related to destroyed windows.
Refactor damage object creation
Cleanup in create_fg_pixmap
Make create_fg_pixmap faster
Function time testing