address Fauck crash on exit

[gewang]

effort to fix Fauck crash-on-exit.

• added a mechanism in Faust.cpp (the chugin binding) to track allocated Faust objects; on VM shutdown (including preemptive external shutdowns e.g., SIGINT or application exit) any outstanding Faust objects will be cleaned up
• added the ability for a chugin to register a callback on host/VM shutdown
• chugin API version is bumped from 10.1 to 10.2 here (note the chugin API version here is currently ahead of chuck tip-of-main; this will be brought to parity on the upcoming 1.5.2.5 release)
• new chugin.h

[shakfu]

@gewang 👍 It worked beautifully!

Awesome! 😄