DeLesley Hutchins (who wrote the original thread-safety attribute functionality) and I have agreed to start migrating from lock-specific terminology to "capability"-specific terminology. This opens the door for future threading-related analysis passes so that a common nomenclature can be used.

The following attributes have been (silently) deprecated, with their replacements listed:

lockable => capability
exclusive_locks_required => requires_capability
shared_locks_required => requires_shared_capability
locks_excluded => requires_capability

There are no functional changes intended.