add a test case

related to PR 13505
try to make the bug report form more robust when the
attempt to get the (nonexistent) captcha fails
Adjust keybinding code to fall back from
get-active-canvas to get-canvas

Unclear if this is a bug in get-active-canvas or not

closes PR 13507
Use up-to-date struct syntax in example
tighten up the checks in the place where the framework receives
values from the lexer (for syntax coloring)
Override readline's getc function to use Racket's read-byte.

Eliminates the busy-polling behavior observed in Mac OS X when
xrepl is required at the regular repl.

Closes PR 13350.
racket/enter: fix for `enter!' related to submodules

The load handler didn't obey the protocol with respect to a second
argument that is a list starting with #f.

Closes PR 13096
clarify colorer docs

Also, some cleanups of the code and
make the syntax-color/ library docs
point to color:text<%> instead of
color:text% (as the interesting information
is attached to the interface, not the class)
Allowing github URLs from PNRs to use illegal package names
Correct hyperlinks to 2htdp/image.
Forbid singleton types for integers whose type is platform-dependent.

Closes PR13501.
Add links to the Wiki from the Community page.
improve ->'s source location tracking

closes PR 13514
add long-missing space
Typo in error message
Changes to move all games to Racket from Mzscheme.

Signed-off-by: Patrick Mahoney <paddy.mahoney@gmail.com>
Misc code improvements, help text typo.
More code therapy.
Some shuffling of text, and a `-wiki' for all wiki links.
"PLT Scheme Inc" -> "PLT Design Inc"