Library updates and some bug fixes

[DBraun]

Bug fixes:

• In between renders, a plugin processor is now better told to turn off all MIDI notes. This is helpful if a render ends before a Note Off event.
• RenderEngine.cpp has fixed an issue when the output render size was off by one sample if the block size was 2.

Other updates:

• JUCE has been updated to 7.0.7.
• pybind11 has been updated.
• Sampler Processor Plugin project has been updated.
• libfaust has been updated to 2.68.1.
• libfaust (the Box and Signal API) files have been refactored into more isolated files.
• The Faust Processor can now load soundfile primitives directly from the filesystem. If the file hasn't been specified via set_soundfiles then the filesystem will be checked.
• • Similar improvement for boxSoundfile("mySound[url:{'tango.wav'}]", 2): If you tell a FaustProcessor to compile the box involving boxSoundfile, then the files will be loaded. As a fallback, the dictionary from set_soundfiles will be used.
• Python floats and ints can be implicitly converted into boxReal(val), boxInt(val), sigReal(val), and sigInt(val): boxHSlider("cutoff", 440, 20, 20000, .001) is OK (440 is implicitly casted boxInt(440)