Extension:CodeReview/code prop changes table

mysql> describe code_prop_changes; +---++--+-++---+ +---++--+-++---+ +---++--+-++---+
 * Field        | Type           | Null | Key | Default        | Extra |
 * cpc_repo_id  | int(11)        | NO   | MUL | NULL           |       |
 * cpc_rev_id   | int(11)        | NO   |     | NULL           |       |
 * cpc_attrib   | varbinary(10)  | NO   |     | NULL           |       |
 * cpc_removed  | blob           | YES  |     | NULL           |       |
 * cpc_added    | blob           | YES  |     | NULL           |       |
 * cpc_timestamp | binary(14)    | NO   |     |                |       |
 * cpc_user     | int(11)        | NO   |     | NULL           |       |
 * cpc_user_text | varbinary(255) | NO  |     | NULL           |       |