set the background and the foreground color (not just the foreground)
when switching to white-on-black mode (or back).

this causes the cursor in embedded editors to pick up the right colors
(since it is selected by the inverse of the background color of the style
of the enclosing editor snip)

closes PR 13943
fix exit:exit docs

closes PR 13944
Update documentation source location link
fix typos in macro guide
Increase DrDr benchmark timeout
Fix mrlib doc typo
Fix guide typo.

Closes PR13955.
fix bytecode-format bug

The range of values used to represent "improper lists"
of length 36 to 65 overlapped with the range of values
used to represent other things.

This bug is the new chapion of the "how did we not hit that
earlier?" category. The bug was introduced around v300, at
the latest.
adjust `compiler/zo-marshal' for bytecode-file change

Forgot to fix as part of b8db5aacb3.
Adjust contract-out so it uses the provide transformer machinery properly

closes PR 13946

This is probably not the optimal way to make this change; better would
have been to refactor the existing provide/contract implementation so
it does not glom the provides all together in the first place (instead
of pulling them out afterwards). Do it this way anyways, because I
have a big pile of contract-system changes in another branch that also
changes around how provide/contract works: this way will be much
easier to rebase those changes off of.
Doc fixes in 2htdp/image
Doc fixes in htdp/image
Doc fix for silly mistake in 495c70c
Make submodule detection more robust.
Make contract profiler robust against empty stack traces.
Fix indentation in current-library-collection-links docs.
Comment typo.
Potentially useful tests
Migrating to new layout
Fix metadata post pkgs