Provides classes to access and manipulate locks.

Locking is an integral part of Slide. Its model resembles in many ways the security model. When one subject (ie. a user) wants to lock another subject (ie. a file), it specifies which actions (for example read) are locked and for how long. Slide automatically checks if a subject is locked before every action. Alternatively, the client application can directly check for whether a particular subject is locked or whether it can actually lock a given subject.