This initial commit introduces a new class Tiling. It is provided by
the files tiling/tiling.h and tiling/tiling.cpp. It covers all the
Tiling functionality which was provided by Workspace. In this initial
commit, all the functions were just moved and adjusted.
A new member variable m_tiling is introduced to Workspace, which
makes the new class Tiling accessible from Workspace.
The Tiling pointer is created in the constructor and deleted in
the deconstructor. Also a getter method tiling() is provided.
All calls from other classes are updated to use the methods in class
Tiling now.
