job and frame status cleanup (move to the model module)
record transitions between states in job to be able to get (among others) the started and finished time.

baking and render options for tags on slaves (default true for both means a slave can do all jobs by default)

use an enum property for VCS job type (much more user friendly this way)

Support for secure connections between Master/client/slave using SSL/HTTPS

Fixed a bug with total job time on web interface (wrong value)

use threading for interprocess communication. Don't stall slave communication when rendering/baking process output blocks. This enables running slow baking and rendering jobs correctly without the slave disconnecting from the master. It also makes slaves much more responsive to cancelling jobs on the master.

add save on job option (default false) to save the current file before sending a rendering blender job.

- distributed point cache baking
- (baking fluids or anything else needs to be added but is not a hard task)
- master support getting all results as a zip (rendering, baking or otherwise), available as a link on the job's page in the web interface
- framework to support multiple result files per frame/task (needed for baking)

wip feature: distributed point cache baking. Distributed baking works but results are sent back to master/client yet. Feature is disabled in the UI for this reason.
new feature: job and slave tags, enables filtering slaves for specific jobs
  jobs are dispatched to a slave only it has no tags or all the job's tags
  Render jobs have the tag "render" by default while baking jobs the tag "baking"
UI: Web interface additions to reflect tags and job subtypes (render/baking)
bug fix: reseting a completed job correctly resets the status to queued

- fix handling of pointcache dependencies on slave (correct repathing) and on client (bad frame dependency range)
- add Force Upload option on master to force dependencies upload and download (don't reuse local copies outside of slave cache)
- add links back to main page on job web page
- client limit dependencies to rendered frame range (it used to add all point cache frames)

Thanks to Philippe Van Hecke for raising the issue by email.

[#29648] patch for netrender: correctly send smoke cache domain

Both by Philippe Van Hecke

Render engine support was expended to be able to specify non-builtin engines.

- remove/comment unused variables
- remove unused imports
- fixed some bugs using incorrect variables

Add rna callback to server address property so that it correctly checks if the server exists when the value changes.