dexts: remove prev and last, they don't exist in dets
dexts: fix some documentation wrongly referring to records
dexts: add count/1 and count/2
dexts: add some docs and specs
table: fix some documentation and specs
table: fix read to take into consideration table type
table: more doc fixes
table: add sequencing
table: add count/1 and count/2
table: implement various datastructures protocols