fix problems with single-flonum (versus flonum) results

The problems were with

 * `sqrt' and `expt' on single-flonum complex numbers
 * `asin' and `acos' on single-flonum arguments and complex results
 * `atan' on mixtures of single-flonum and exact arguments
 * `gcd' on mixtures of single-flonum and flonum arguments
math/matrix: fix some duplicate documentation tags
try to make this test's timing better behaved
batch io functions now accept 'standard-[in,out] in lieu of file name
adjust scribble/lp language so drracket syntax colors it properly

Also fix a spelling mistake (now that spell checking works) and Rackety
change chat noir so that 'h' toggles help

(instead of requiring it to be pressed down all
the time, as that generates lots of extra events)
supporting http proxy (without authorization) during make install
setup/configtab: prevent cross-module inlining of configuration

The intent is that the configuration module can be rewritten without
recompiling code that uses it, so don't let the compiler inline
configuration values.
minor README correction
raco exe: yet another submodule repair

Closes PR 13410
guard call to file-or-directory-permissions

related to PR 13359
also, Rackety
re-enable autosave only if a save is successful, not just attempted

when combined with 94b54db11823b4683234424174aca2836d422204,
closes PR 13359
remove 'create executable' functionality from drracket for all
langauges except The Racket Language and the HtDP and DMdA languages
move a literal string that should be translated into the string-constants library
added defthing as a doc feature; Closes PR13414
added stdin and stdout as alternatives
try to make the colorer more friendly when there is an unclosed
edit sequence

(ie make it not take over the cpu)
add missing inner call
Merge branch 'master' of https://github.com/plt/racket