Description:
------------
Case folding is against the XML standard, as stated in:

http://markmail.org/message/exlh6us4wpbt7juk#query:xml%20case%20folding%20xml-dev+page:1+mid:rikx6p3veteu5und+state:results

and:

http://www.xml.com/axml/notes/CaseSensitive.html

A previous bug was submitted in 2003 about this issue; the decision then was that backwards compatibility trumped adhering to the standard.  I'd like to resubmit this issue for consideration, with the following arguments:

* XML is a standard.  As such, people expect XML parsers to all 
  behave the same way within reasonable limits.  Violating the 
  standard is definitely something people never expect the parser to 
  do.

* Backwards compatibility is important, yet there are ways to  
  mitigate the problems.  Deprecation warning are used a lot.  
  Unfortunately, they'd be fairly tricky in this case.

  I guess one way would be to have a flag in php.ini to use
  the old default.  And also perhaps have a version
  of PHP (with the same default) that spat out warnings if the
  case folding setting isn't user-set *with a note about the
  php.ini flag and that the default will change next version*
  (of course the warnings would be disabled if the flag is set).

  As evil as that would be, it's the only deprecation warning
  scheme I can think of (not that I have the slightest
  experience deprecating aspects of APIs or languages :) ).

* Finally, to expand on my first point, since case folding is against 
  the XML spec, enabling it by default screws everyone over who is 
  using XML precisely because it *is* a standard.