Update 00-intro.md
Add test case for removing unused dependencies on whitelisted update
Add test to verify that depency packages get deleted when no longer in lock file
add --prefer-lowest-stable to update command
split update --prefer-lowest and --prefer-stable
Fix HHVM interop
Point users at troubleshooting if they get known exceptions
Merge remote-tracking branch 'PaulSchell/patch-1'
Fix wording, refs #3466
Merge pull request #3467 from naderman/fix-update-whitelist-unused

Add test case for removing unused dependencies on whitelisted update
Fix parsing of strings, fixes #3543
Avoid loading plugins that have had their code wiped from filesystem, fixes #3115, closes #3538
Enough intermittent failures already
Make sure global plugins are purged as well, fixes #3115
Suppress errors when creating global composer
Fix bug when installing
Fix tests
rewriting some documentation sections
scrapping next line
Merge pull request #3551 from alcohol/minor-documentation-adjustments

WIP: rewriting some documentation sections