Cells and mapping cells to/from locs

Changed the representation of cells to dotted pairs.  Changed the way excluded squares on the board
are represented and handled.  Added mapping arrays for converting from cells to locations and locs to cells.
EBMS Structures

Added an ebms structure for storing the move-schema information in the *spaceindex*.
This should help during future changes as fields are added or removed so we don't have to
keep fiddling with the vector indices.

Finished updating the dotted-pair cell representation changes in stp-init.rkt.

Rearranged some of the tests in can-move? and reduced the time to generate the spaceindex
to less that half of what it was.
add CP24 init