Split game & editor keyhandling

* added Camera::moveToLocation(MapLocation)
* Camera(MapLocation) now calls Camera::moveToLocation()
* added Game::movePlayer(int dx, int dy)
* added Game::handleKeypress(int key)
* added Game::m_advanceTurn that when true, advances the turn at the
end of each tick
* tab now switches between editor (blank screen) and game
* editor camera now properly used