Fix compilation on Ubuntu. Improve integration with Qt5.
Fixed a bug of player jumping after he stops climbing *any* hill.

Also accidentally restored original intention of jumps following a normal to the ground.
The bug was that the logical condition for player standing on the ground and not running didn't take jumps into account.
Closes #16.
Fixed #issue3

Currently game doesn't crash while simultaneous shooting and grenade throwing, it was caused by pure virtual function getType in Entity. Further investigation needed.