Add tests for empty case-lambdas in apply.
Make apply of poly functions more like regular functions.
Make polydotted * case in apply similar to other cases.
Merge different cases in tc-apply.
Pull out typechecking subexpressions in tc-apply.
Simplify failure case in tc-apply.
Simplify poly drest case in tc-apply.
Remove extraneous check.
Simplify different cases in poly tc-apply.
Add match expander for all polymorphic functions. Use it in tc-apply error messages.
Merge poly and simple function cases in tc-apply.
Add comments to tc/apply.
Add explicit -Null abbreviation.

Also clean up many use cases of -pair and (-val null) with -lst*.