Miscellaneous functions

`Abort`	Terminates the current transaction.
`Class`	Returns the ref for a class (or collection).
`Classes`	Returns an array of refs of all classes (or collections).
`Collection`	Returns the ref for a collection.
`Collections`	Returns an array of refs of all collections.
`Database`	Returns the ref for a database.
`Databases`	Returns an array of refs of all databases.
`Function`	Returns the ref for a user-defined function.
`Functions`	Returns an array of refs of all user-defined functions.
`Index`	Returns the ref for an index.
`Indexes`	Returns an array of refs for all indexes.
`NewId`	Generates a unique, numeric id.
`Ref`	Returns the reference to a specific document in a class.
`Role`	Returns the ref for a user-defined role.
`Roles`	Returns an array of refs of all user-defined roles.