Minor commit, fixing a small bug in the documentation.
Merged master into fix-abstraction after a while, removed an unused
interface, and cleaned up the build process a bit by removing an unnecessary
interface file, got rid of an obsolete
file named calc.ml and its noweb form, also some general housekeeping of Makefile content.
Got rid of a bit of experimental code from way back.
Replaced the constraining mechanism with another which does not use constraint_t and uses (i, j, strictness, bound) instead.
Removed all references to raw_t pointers being sent to Ocaml.
Removed all references to constraint_t pointers being sent to
Ocaml. Also, made a slight change for prettiness.