Merge pull request #20 from denpaforks/master

Check that lock file exists, before trying to delete it.

add LockSet

closes #4

Merge pull request #12 from texthtml/feature/factory-interface

add \TH\Lock\Factory interface

Merge pull request #10 from mathroc/feature/cleanup-identifier

remove $identifier from LockFile

stabilize deps

don't wait for exclusive lock to remove file on release

Fix issue found by Scrutinizer

only remove locked file after release for lock file created with factory