(1) Moved all routines into LayerMapping class (for easier subclassing) and modularized the routines.
(2) OFTString and OFTReal OGR fields are verified w/the Django fields prior to insertion, thus avoiding invalidating a large transaction.
(3) Added keyword options for specifying the transaction mode, not performing transformations, and status printing.
(4) Created unit tests.
Other Changes:
Updated `ogrinfo` for GDAL refactor and fixed an iterating bug; simplified a few lines in `geoapp` model tests.
git-svn-id: http://code.djangoproject.com/svn/django/branches/gis@6687 bcc190cf-cafb-0310-a4f2-bffc1f526a37
