Merged from 5.0 version of this patch:
- Removed entire isamchk section. Support for ISAM tables was removed in 5.0.
- Replaced key_buffer with key_buffer_size (correct spelling).
- Removed skip-bdb, as BDB is no longer included in 5.0 and above.
- Removed commented-out bdb_cache_size and bdb_max_lock for the same reason.
- Removed commented-out innodb_log_arch_dir, deprecated in 5.0.24.
- Removed myisam_max_extra_sort_file_size, deprecated in 5.0.6. 
- Removed log_long_format, deprecated in 4.1.
- Replaced default_table_type with default-storage-engine.
New in 5.1:
- Replaced table_cache with table_open_cache.
- Removed skip-federated, should have been in 5.0 only.
- Replaced log_slow_queries with slow_query_log, deprecated in 5.1.29.