WIP - Rough first pass adding a "lens" for viewing a board. Limits
the view too much. Doesn't move or scale yet
WIP - minor progress on lens feature. text display works but lens isn't
being moved or doing very much
WIP - basically works in text mode. Held together with shoestrings
WIP - Made lens auto-center display. Simplified front-end lens
interaction by adding x and y display_offset varabiales to lens
WIP - "works" with the graphical front-end now. Formulas for
calculating offsets in the lens aren't quite right
WIP - Added calculation of scale for lens. Switched sign of offset
Fixed typo of break in lens_move
WIP - Fixed logic in lens_move
WIP - Removed board argument to lens_move functions. Moved x,y offset
validation to lens_set. stubbed out graphical-ui controls
Added controls to graphical front-end. added arrow keys to both
Added comments/docstrings to lens
Added lens movement instructions to usage string/README
Changed data files back to pre-testing values from develop/master
split lens_set into 3 smaller functions. Added lots of docstrings. Made
text display always set lens' scale to 1
Fixed a bug where scale wasn't set to a value before being used. Broke
up the lens_set functions a little more. More comments
Added a docstring for the lens.c module
Moved lens module docstring to header file
Made lens move by more than one cell at a time, (currently 5)
Merge pull request #3 from calebsmith/feature/add-lens

Added a "lens" to separate the display of the board from the board itself