Improved streamBuffer memory policy in Synth:
- streamBuffer size is now set to 512 initially and grows up to 32K when a long SysEx encountered.
  While we deal with SysEx messages below 512 bytes long in most cases, it seems reasonable to support a possibility
  to load bulk dumps using a single message. However, this is known to fail with a real device due to limited input buffer size.
- fixed probable memory access to unallocated region in parseSysex()