prove FV_decs evaluation in the bootstrap theory

adds about 7 minutes; not sure if this calculation of free variables can
be avoided or sped up but it's not too bad in the grand scheme of things...
reduce the cheats in bootstrap_lemmas to EqualityType INPUT_TYPE

which I am not going to prove since the translator should already know it
delete old stuff from bootstrap_lemmasScript.sml
delete unused bootstrap files and update README