Non-polymorphic type parameters are printed in the correct order.
Added a flag to enable effect system output.
Marked parameters from same skeleton with same letters.
Enabled simplification of schemes.

Negative parameters are replaced with their
unique successors, if there is one. Similarly,
positive parameters are replaced with their
unique predecessors.
We do not print inequalities between equal parameters.
Enabled UTF-8 output.
Validated tests with new handler type parenthesizing.
Merge branch 'feature/pretty-output' into develop
Fixed a bug in Unicode printing.
Removed unnecessary trim_context of poly
Non-polymorphic vars get into environment as well.
Skipped adding unnecessary changes in infer for Core.Let
New top inference mechanism.
Fixed computation of skeletons.
Fixed joining of disjoint constraints.
Validated tests.
Moved nonpoly from vars in Infer.infer_let.
Moved nonpoly from vars in infer_comp
Infer.infer_let and infer_let_rec return a dirty-scheme change.
Moved to keeping a global change.