Fix parser for command line options

-g  "C:\Users..":   The folder that contain .map files

 -t "tiles":              The folder that will contain tiles (Optional)

-z 8:                     Zoom level 4-n. Number of tiles to extract around position 0,0 of map.
                            It is in the form of 4^n tiles.It will extract a grid of 2^n*16 tiles on each side.(Optional)