Make some attributes private

I think my Python is a bit rusted but I will get there...
Add tesseract-based OCR for parsing the map coordinates

For a given ImageMagick Image, we parse the coordinates and output
a decimal degree float as result.
Add parser for the X and Y coordinates

This patch also adds the magic bounding box and offset of the
coordinates that I hope will work on every map format.

The coordinates placement seems to be aligned with the map corner. The
font also size also seems to be the same. Fingers crossed.