[plt-scheme] case-sensitive reader by default

I vote no.

My reasoning is that the main reason, afaict, for case-sensitivity is to
support interoperation with external environments which are
case-sensitive.  This seems to be an area where the notion "code is data"
runs into the problem that the reader has to be able to understand various
kinds of external data that don't necessarily otherwise make sense in
code.

However, this requirement seems to me to be well taken care of by the
ability to selectively enable case-sensitivity, where it's needed.  All
that's really needed is a SRFI for that, which implementations respect.

As a matter of interest, there's a small survey of CS teachers on the
subject of case sensitivity in Python, here:

http://www.thinkspot.net/sheila/computers/case/surveyquestions.html

Regarding interoperation, I'd like to take this opportunity to vote for
making Unix file systems case-insensitive...

Anton