Control internal Fixture Behavior with nodes

[maxjoehnk]

Allow a node workflow to control the internals of a fixture.

This would resolve #117 and #62 as this functionality could be built within the fixture node. There should be a way to expose new fixture controls which are not present on the definition for this to work.

~~There should also be a way to reference other nodes from the main pipeline so a fader node can be read from the fixture pipeline as well.~~ I don't think this should be a feature. Instead one should create a new fixture control for this. If #245 becomes a feature this could also solve this problem.

There should be node templates for virtual shutter and submasters which can be applied to multiple fixtures at once.

[maxjoehnk]

Instead of controlling the pipeline for each fixture you should be able to choose the internal pipeline in the fixture patch. Each fixture should have it's own instance of the selected pipeline,

The pipeline should have 2-3 node types which are only available in fixture pipelines:

FixtureOutput This provides the actual outputs translating to dmx. It has ports for each fixture channel.

FixtureInput By default one input per channel in the fixture definition. Allows configuration of the fixture control channel this input represents. The node configuration should forbid duplicate inputs per control except for custom controls. The value output should be of type multi to allow control of the order of the values written to the fixture. E.g. Highest, Lowest, Latest, First or whatever else a user might think off.

FixtureSettings Not sure about this one yet but could provide a way to read options like pan/tilt limits, direction flip, 3D position.