libs: EventQueue: Zero keypress bitflags on init.

Each event carries bitflags of currently pressed keys, these flags are
recorded in bitflag array in the the EventQueue and must be initialized
to zeroes prior the use.

This fixes bug where some of the keys were wrongly reported as pressed
at the start of the application.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
spiv: Large scale cleanup.

This is large scale cleanup in spiv which is much needed before the
functional changes.

This also fixes several bugs that were not posible to fix before the
cleanup, namely:

* Image that doesn't fit to the image cache is now freed
  (this bug was there since the implementation of the cache)

* Image size in info box is printed correctly even when
  image is rotated

+ numerous small fixes

Signed-off-by: Cyril Hrubis <metan@ucw.cz>