Determine auth URLs more intelligently
Add blank line to output for FileDownloader.

The VcsDownloader outputs a blank line between each dependency:

https://github.com/composer/composer/blob/745dcbce3317f7119575c39cef2cb601f9c5ffcf/src/Composer/Downloader/VcsDownloader.php#L80

This write makes output consistent.
Option to disable inclusion of hostname in OAuth app name
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
When $TMPDIR is low on space PHP streams silently fail
Handle incomplete file write to cache
Very tiny but necessary edit

To delete `.git` repos of submodules, `rm -rf vendor/**/.git` doesn't work, but `rm -rf vendor/*/*/.git` does
update documentation to work for ZSH or Bash
docu fix (removed dangling "times." introduced by 22afc074a96d27b5462d335e22da893570bf7e87)
Fixing a typo in the scripts documentation
updated package variable in gathering requirements
Fix missing validation on default value for author input

The default author value on the composer init command is not validated against `parseAuthorString` method and thus not being re-prompted, finally throwing an InvalidArgumentException when it tries to generate the composer.json file.

The changes forces the validation of both the entered author string or the default value.
Allow to select virtual packages
Accessing to option 'optimize-autoloder' inside 'post-autoload-dump' script event.
Changed short array syntzx to long