Switch to statically-linked cmake build

[Birch-san]

Remake build system in cmake, for a few reasons:

• make it easier to build for a variety of OSes and architectures
  • our project templates have diverged a lot from the Projucer template
    • because libraries are dynamically-linked
    • we provide an installer for Windows (to help put the dynamic libraries in the right places)
    • we rewrite the load commands in the libraries on OSX so that dependencies are "bundled in"
• get a recent release
  • to support M1 Macs
  • update Fluidsynth (to fix the sustain error)
• make it easier to drive builds via CI
• make it easier to support your favourite IDE
• support static linking (for easier distribution)

Current status:

• AU plugin builds, but creates a horrible noise even when idle
  • my first guess is that a double-precision audio buffer is being sent to the float overload of processBlock; need to check this in debugger
• VST2 and VST3 plugins build
  • I've not been able to test the VST2 plugin inside JUCE's Audio Plugin Host
    • (probably was built without VST2 SDK)
  • the VST3 plugin works perfectly inside JUCE's Audio Plugin Host
  • VST2 and VST3 fail to load in FL Studio
• standalone application builds; works perfectly