porting disis_munger~ from C++ to C

This extracts the ADSR class from stk and tries to port disis_munger~ to C.

This is just a draft atm-- it's not ready to compile, but all the major functionality is there.

Todo:

• port flext Buffer to either t_array or garray
• make sure samplerate stuff updates when changed in Pd
• add to disis makefile
• make several more passes through
• attempt to compile :)