Updated JsonHandler to add the .json extension to files without any extension. Before it would try to save the file as "json".
Allow the Camera's boxes to be set by x,y,w,h parameters.
Allow maps to get/set Filename, Rows, and Columns. Also changed the Load method to catch and handle bad input.
Added tilename parameter for the MapEditor's GenerateBlank() method. Also removed the x,y parameters because we can just rely on the rows & columns Map variables.
Added dialog boxes to the Editor.

  Press 'a' - Save As
  Press 's' - Save
  Press 'n' - New blank map (prompts for rows & columns, defaults tiles to the currently selected tile in the tilebar)
Defect Fix: Added tilename parameter for the MapEditor's GenerateBlank() method
Merge pull request #29 from btstevens89/master

Changes for the MapEditor