fix traditional/simplified initial choice
allow multiple string constants to be in a single "line"

also enforce some spacing requirements to avoid the problem
where you forget to put a space in a message that is broken
across string constants.
planet2: installation-wide config of default `raco pkg' scope

With either
  configure --enable-pkgscope=installation
or
  raco pkg config -i --set default-scope installation
the default scope of `raco pkg' actions can be changed from
user-specific to installation-wide.

We considered trying to guess when someone building Racket would prefer
installation-wide package scope by default. In particular, someone
building from source for in-place use seems likely to want
installation-wide scope by default. Then again, we don't want to
discourage in-place builds for Unix installations that are intended
for multiple users. So, no guessing for now.

Also, add a `--scope' argument to `raco pkg' commands, which is more in
line with other options, but keep `-i', etc., as shorthands.
add deprecation notice to mrlib/cache-image-snip
speed up tab switching

I belive this should only be noticeable at the human timescale level
when the tabs have been switched to already and, in that case, seems
to go from 3-400 msec to 50-60 msec on my machine

Essentially all of that time is in redrawing the buffer, so that 50-60
msec is proportional to the height of the DrRacket window, roughly.

(The commit just makes drracket do a single redraw instead of about 4
or so of them per switch ...)
Minor rewording
Add examples & slight fix for stxparam docs
Fixing PR13409
add check for number of result values in ->i (that signals blame)

closes PR 13417
add planet2 info to the bug report system
Extend type of min to preserve fixnumness.
Merge branch 'master' of https://github.com/plt/racket