rename |make-board*| to |board|
define and use board-dim
move lib stuff
move board code to separate file
more unused libraries
rename round to Round (to avoid conflict with round number function)
|def|: allow types
check input to |board|
efficient destructive set
move internal-pos? check to before board-pos->field-index call

so that it doesn't query the set with positions outside the board
remove doubting comment
move set implementation to separate file, add maxsize argument
comment about destructive but still functional
turn back to safe choice for set for now
fix tests for functional implementation

hah