FILEIO: Added saving and loading of Map to/from file

* Walls and Points of interest are serialized and saved to a user
specified file in binary format using QSettings
* Walls and Points of interest could be read from file and
imported to a map
* Star ('*') indicator added to titlebar if map has been modified
* Added dialog to ask if user wants to save the unsaved changes before
quitting or opening new file
* Added program name and filename to titlebar