Initial saving created #7. Json added to support loading sets, saving
maps and later on loading maps
Loading maps functionality added #11

Minor fix to top menu positioning as well
Cleared up log messages
loadedTexture vector has been made static and moved into the texture
wrapper base class. All implementations should add themselves to the
vector.

Drawing area is started without a default tile, and handles NULL for
current tile
Removed warning
#13 Ok dialog created, layout needs improving.

Yes/No & Input dialogs not implemented yet