backporting store locking
added test for readonly databases not being allowed to share store files
backporting store locking
Merge pull request #542 from lassewesth/storelockingbackport

backporting store locking
Fixes bug on windows around the new store locker, where the store lock will be attempted to be grabbed twice.

Locks are now grabbed only on store_lock file on windows
Adjusts TestOsSpecificLocks accordingly
Makes the new line character non platform specific, fixes windows failures
Updates changelogs for 1.8.2
Grabs store locks a bit more defensively, to guard against failures during startup

Store locks are now grabbed as a test in IAGD.create() and released immediately. They are
 grabbed again as part of lifecycle.