Update to allow preset loading

[cannoneyed]

Right now, RenderMan is configured to render random synth patches - this PR adds in a few methods to load a preset file and set the parameters of the VST plugin from that preset, as well as setting parameters manually.

In order to make things a little more compatible with the previous API, I've simply added an overridePatch parameter to the renderPatch method, which allows for the user to call the method with either the manually applied parameter settings or the random "override" patch.

A better API would be to have two separate methods - renderPatch (which simply renders audio) and setRandomPatch that splits random patch generation away from rendering. I'd be happy to make these changes if this feels like a reasonable direction.

[fedden]

Hey @cannoneyed thanks for the PR. I'm unable to support this project in a professional capacity, so I am wondering if you would like to become a collaborator to get this project in a state that is hopefully usable for yourself and others?