Read Fields out of proto instead of FRM.
As non-radioactive fallout:
- no implicit defaults (see http://bugs.mysql.com/bug.php?id=43151)
- no real defaults for BLOB yet... but this paves the way (and it shouldn't be too hard now)
As radioactive fallout:
- parse_table_proto is approaching the length of War and Peace
- handling of corrupted proto is about non-existant. abort() is not ideal