Fix meta length parsing for >127 byte entries
Fix meta length parsing for >127 byte entries

In find_note, the meta_len was hardcoded as a single byte encoding, but per
the spec and some files with long comments and copyrights, it is actually
encoded as a varlen.  Use the varlen parser (which defaults to the old
behavior of 1-byte for <128 len fields) instead.

LenShustek/miditones