move the slideshow/pict library to its own collection

also, adjust all of the requires in the tree to point to the pict
collection
disable slideshow's addition (to drracket) of pict value rendering
add responsible for collects/pict
Fix type of sinh.

Found using random testing.
Limit memory in all sandboxes used by the TR random tester.
Make `define-type` work at top-level

Closes PR 12913
Fixed bad let syntax
Hacky fix to only flatten repeats
Added Redex enum tests
Removed tabs from redex enum code
add enum-tests into run-tests.rkt
Fix source locations for TR for.
Log sequence specialization failures in `for' loops.

Using this logging, Optimization Coach can recommend adding `in-list'
and co. to `for' loops in hot code.
Fix test for TR's for source locations.
Add more syntax examples to the reference
Fix tc-toplevel-form for ignored syntax
Make `require/typed` work at top-level

Closes PR 13747
Refactor to reduce right-ward drift
Whitespace and comment fixes
adjust contract test suite to do more provide/contract => contract-out
rewriting in order to test contract-out more