This patch extends Table Map Event. It appends some new fields for
more metadata. The new metadata includes:
- Signedness of Numberic Columns
- Character Set of Character Columns and Binary Columns
- Column Name
- String Value of SET Columns
- String Value of ENUM Columns
- Primary Key
- Geometry Type

Some of them are optional, the patch introduces a GLOBAL system
variable to control it. It is binlog_row_metadata.
- Scope:   GLOBAL
- Dynamic: Yes
- Type:    ENUM
- Values:  {MINIMAL, FULL}
- Default: MINIMAL
  Only Signedness, character set and geometry type are logged if it is MINIMAL.
  Otherwise all of them are logged.