The organization here is now the same as for the Timidity++ device, i.e. it is the device owning the instruments to give better control over their lifecycle.
* use std::string instead of FString
* replaced the single use of clamp with std::min/std::max.
* copied MAKE_ID macro into the source.
* use snprintf instead of mysnprintf
* use std::runtime_error instead of I_Error to abort on failed memory allocations.
