Fix type of set?. Closes PR13509.
Fix heterogeneous vector typechecking.
[honu] mark/unmark syntax parsed through the expression syntax class
[honu] many small things: allow with syntax to bind arbitrary patterns. provide time and time-apply. make compress-dollars recurse on sub-expressions. add an implicit pattern variable that consists of the result with an ellipses depth of 1. fix the while form. allow require forms to contain mostly anything and be separated by commas.
[honu] fix lexical context for require forms. fixup the module name to replace _ with -
autobib: add #:spaces argument to define-cite that puts N spaces between each bibliography entry
autobib: document #:spaces keyword
adding common special for the wrap-proc of the chaperone for option contracts on procedures
Minor sandbox improvements.

* Check `sandbox-path-permissions' for bad values such as
  '(<perm> <path1> <path2>) where <path2> would get silently ignored.

* Try to clarify the intent of `call-in-sandbox-context' as a meta tool
  rather than a safe execution tool.
Remove use of mzscheme fluid-let in favor of parameters.
scribble/manual: add `#:id' option to `defthing'

Use this open in the HtDP language documentation in the same
way as for `defproc', which fixes the docs for `pi', `e', etc.
redex: fix `metafunction->pict' width correction for linebreaks

The revised implementation is more clearly and directly expressed
in terms of table cells that span columns.

Also, avoid `panorama' by removing a useless `inset' that seems
likely to be the reason for the `panorama'.

Unix bitmaps to go with the new tests are missing; Robby plans to
add them.
Fix pattern unification to deal with #f correctly
Bitmap test adjustments

- fill in unix bitmaps
- combine the horizontal metafunction test cases into a single bitmap
tweak arrow contract expansion to make the output a little easier to read
properly handle eof in the online expansion code

It used to just kind of give up processing which, from the outside,
watching looked like

  (begin-for-syntax (custodian-shutdown-all (current-custodian)))

and so fell into that case in the code. Now, by explicitly raising
an exception, we get a more accurate response
fix a with-handlers to avoid catching break exns
bring 'jump to definition' more in line with online check syntax

That is, when right-clicking on an imported identifier, if the
file that has that identifier's definition is open and online
check syntax has completed, then offer a "jump to definition" menu
item that just jumps there with the already computed informtion.
If the file isn't open or online check syntax hasn't completed,
instead offer just to go to the file, without jumping to the definition

also
- things should generally work slightly better with submodules
- jumping to identifiers should do a better job with scrolling,
  specifically it should scroll so the jumped-to identifier is
  about 20% from the top of the window (unless it was already visible,
  in which case no scrolling should occur)
bring mac os x bitmaps in line with recent commit made for the linux bitmaps
use clipping in the recent commit to actually test bounding boxes