tg-extract-results: Add cell-based accuracy
Poligrounder: Remove unneeded code
Geolocate.scala: Clean up computation of cell grid size and output differing measurements
ConvertCophir: Remove broken bulk-upload code and add long comment about implementing proper user frequency counting
Add some code to help implement a user-frequency model (O'Hare Murdock 2012)
textdb: Rename files to follow foo.data.txt, foo.schema.txt format
bin/textgrounder: fix typo
simplify output of textdb files: just a single base rather than dir/prefix/suffix
Document: Remove unused GeoDocWriter
textdb: filehand argument not needed when constructing filenames
Reject documents that become empty after stopword/etc. elimination, to avoid NaN's; signal errors when bad prob values returned; improve error messages