Don't splice in vector creation when optimizing vector-length.

Closes PR13788.
Fix broken test.
Added some checks for user errors.
Removed some error-checks that can't happen.
Added a bunch of test cases.
Reorganized test cases to be after each function, rather than all in one place.
add a parameter to adjust random generation methods

- also remove an obsolete function and some other cleanups
Fix broken test, again.
Use submodules instead of marking tricks for identifiers in docs.
Register scoped type variables for internal def. annotations.

Closes PR 13793.
Make resolve actually do all the necessary resolutions.
Centralize the definition of the plambda syntax property.
Centralized typechecker:ignore properties.
Consolidate the rest of the syntax properties in TR.
Make for loops in TR use an annotation when applicable.
Use in-syntax instead of in-list/syntax->list.
Add syntax-length to unstable/syntax.
Make TR use syntax-length instead of (length (syntax->list x)).
Move from syntax-map to stx-map.
Move from syntax->list and map to stx-map.
Add error checking to in-syntax.
Replace syntax-map with stx-map in unstable/automata
Replace syntax-map with stx-map in plai.