Added a footstep sprite to defaulttileset.
qrw::BoradWidget now renders footsteps for path.

No longer using those ugly red bulbs :D
Added qrw::Path::getStep().
Added missing delete in CoordinatesTest.
Added qrw::Coordinates::operator-().
qrw::BoardWidget::drawPath() now draws footstep sprites.
Added 45° rotations of footsteps.

The footsteps are rotated by 45° if the pathe takes a corner.
Merge pull request #63 from namelessvoid/footstep

Added visual footsteps.

The BoardWidget now shows the path found via pathfinding in a nicer way by using a footstep sprite.