Updated: setup (2.883)

[Jon Turney]

A new version of Setup, release 2.883, has been uploaded to

   https://cygwin.com/setup-x86.exe     (32 bit version)
   https://cygwin.com/setup-x86_64.exe  (64 bit version)

Changes compared to 2.882:

- Various improvements to behaviour after a download error
- Don't fatal() on unexpected early window messages
   (Addresses: https://cygwin.com/ml/cygwin/2017-07/msg00428.html)
- Remove support for installing from a local directory which doesn't 
contain a setup.ini file
- Make 'System Proxy Settings' the default (for new installations) on 
the 'Select Connection Type' page, rather than 'Direct'
- Fix reading and writing of the "extrakeys" user setting. Maybe -U/-u 
does something useful now?
- Pressing enter in the URL textbox on the "Choose Download Site(s)" 
page now does 'Add', rather than 'Next'
- Pressing enter in the search textbox on the "Select Packages" page now 
causes the search to be performed, rather than 'Next'
- Fix concatenating depends: from each version description section
- Bullet-proof the way we remove empty categories
- If more than one download site is used, we now require downloading 
setup.ini from all of them to succeed, rather than just one of them.
- Various code rearrangements and simplifications

Thanks to Ken Brown for several of these changes.

Please send bug reports, as usual, to the public mailing list cygwin AT
cygwin DOT com.