Change default value of 'Slim' parameter to 0.0

[sdatkinson]

Description

Little quality-of-life improvement (IMO): slimmable models will load at their smallest size to start; users can adjust the parameter to increase from there.

Reasons why:

• CPU usage is, by far, what most users are most sensitive to.
• Less technically-literate users are less likely to understand how to adjust parameters in the plugin; power users will have more CPU, be more interested in accuracy, and will (probably) figure out how to change it.
• Makes it less risky that CPU usage will buckle under the weight when the model is newly-loaded--"start small".

PR Checklist

• Did you format your code using format.bash?
• Does the VST3 plugin pass all of the unit tests in the VST3PluginTestHost? (Download it as part of the VST3 SDK here.)
  • Windows
  • macOS
• Does your PR add, remove, or rename any plugin parameters? If yes...
  • Have you ensured that the plug-in unserializes correctly?
  • Have you ensured that older versions of the plug-in load correctly? (See Unserialization.cpp.)
• Does your PR add or remove any graphical assets? If yes, are they defined in config.h and added in the two required locations in main.rc?