Stub out independent instruction parser.
Add test stub for instruction parser.
Implement basic parser test.
Implement length parse.
Implement rest of parser.
Fix test's assumptions regarding contract of parser.
Partial re-implementation of parse.
Use simpler pointer arithmetic to determine buffer regions for reading and parsing.
Fully init allocated instructions.
Handle Unicode characters in input.
Shift buffer to gain space if necessary.
If length parse fails, return need for more data.
Allow continuous parsing of length, rather than restarting if unfinished.
Do not restart parse - just shift everything as necessary.