Follow 480afa4c4de10ff428521405b6b9718a1edba055 in deinprogramm.

Abstract out the teachpacks dialog and re-use in DMdA languages.
Add (very simple) type for `hash`.
fix the conversion to a [0,360) interval for angles in 2htdp/image

closes PR 14071
Fix TR constructor detection.

Was accidentally turning #%expression into #%plain-app in some cases.
fix image list coercion

unbreaks place-image in the case that it gets bitmaps directly

Also, bring test-image.rkt down below 102 columns
test for stop-when problem with booleans
fixed test with display line
Added `point-label3d', notion of layers (back, area, front) to 3D plots
fix persistent bug in terminating universe via clock limit
fix bug with boolean result check in stop-when, Rackety
Fix props for cext-lib pkg.
fix dict-empty?
  closes PR 14075
fix attr check for ~optional defaults
  closes PR 14076
fix name of struct constructor built by struct-out

closes PR 14073
raco setup et al.: fix problem with relative paths that exit a collection

Closes PR 14063
fix test for previous commit
Increse timeouts.
fix typo
better "expected more terms" messages in some cases

Still need docs, make constant stxclass descriptions available
updated tests