Work toward functioning items and inventory

*fixed a bug in font rendering (should have been signed)
*fixed a bug in font rendering (texture offsets were wrong)
*added rect drawing functions (text background etc)
*added accessor functions to get the actual extent of text layouts
*moved more json field names to a central location
*added a json utility class to consolidate locale file parsing
*made item generation draw from the .def files instead of the old
temporary list
*properly erase old inspect messages when the view changes
*added a parser for json item def files