Updating the LISA reference manual.
Planned inclusions: ✔ OCBSL OL equivalence ❓ Updated printing and parsing syntax ❓ Abstracted proof syntax ❓ String/Sequent equality || DSL ❓ Basic Tactic system ❓ Tactic composition and sequent manipulation ❓ Imperative composition of tactics ❓ Tactic building with kernel steps ❓ Substitution abstraction