Determine auth URLs more intelligently
Update troubeshooting.md to suggest clearing Composer's cache.
added test unlinking directory

#3157
rmdir needs to be used on windows to remove symbolic links to directories
added test removing directory with trailing slash that is symlinked

#3144
#3157
unlinking symlinked directories and trailing slashes

Filesystem::removeDirectory() didn't detect all symlinked directories
properly due to not resolving pathnames with trailing slashes first.

this commit fixes that issue by resolving pathnames with trailing slashes
by removing those in case they are representing a symlinked directory.

#3144

Reference:

 A.4.12 Pathname Resolution - The Open Group Base Specifications Issue 7
 IEEE Std 1003.1, 2013 Edition Section
 <http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap04.html>
added stof's php inline example from #3190 to doc/articles/scripts.md
docu fix (removed dangling "times." introduced by 22afc074a96d27b5462d335e22da893570bf7e87)
Fixing a typo in the scripts documentation
updated package variable in gathering requirements
Fix phpdoc
Merge pull request #3321 from francoispluchino/fix-phpdoc

Fix phpdoc
Allow to select virtual packages
Adjust APC check, refs #264
Accessing to option 'optimize-autoloder' inside 'post-autoload-dump' script event.
Changed short array syntzx to long
Fix json test, fixes #3326
Merge pull request #3327 from Strate/dump_autoload_event_args

Accessing to option 'optimize-autoloder' inside 'post-autoload-dump' script event
Fix json nesting issue, fixes #3323
Merge pull request #3257 from jakoch/patch-docufix

docu fix (removed dangling "times.")