Synchronize _txData structure
Remove ScopedLock
Add URL endpoints
Fix issue by actually returning true
Filename typo
WIP - fixup later
Make TXContext serializable
Implemented begin/commit on sessions
Add session context pickup in RequestParseTask
Reduce error reporting + TODO
Several TX changes

* Documented TX interface
* Spinlock now has stl-compatible naming
* prepareCommit now always locks
Move functionality into Request/Response

* add basic tx tests
* add educational python client
* remove http routes
Implement transaction as Op, not via url parameter as discussed with @grundprinzip