[ADD] Core, Locking: Tests for database locking inside BaseX
Merge branch 'master' of git://github.com/BaseXdb/basex into locking
[ADD] Core, Locking: Simultaneously read&write-lock databases
[ADD] Core, Locking: Lock Downgrading support in DBLocking
[MIN] Fixed rare deadlock in locking test code
[FIX] Core, Locking: Fuzzy testing and fixed deadlock
[FIX] XQuery Update: removing buggy memory-saving optimization
[FIX] XQuery, JSON Serializer, output of element names. Closes #614
[MIN] Core, Locking: Cleanup and small fixes

- enforce preclaiming locking
- use fair scheduling to prevent starvation
- some refactoring
Merge branch 'master' of git://github.com/BaseXdb/basex into locking
[MOD] Core, Locking: Disable database locking in GUI
Merge branch 'locking' of https://github.com/JensErat/basex into tmp
[MIN] Core, database locking: minor rewritings