- fixes platform's COMMENT ON statement support
- implements reverse engineering for column comments
- marks boolean column type commented for distinction

fixes #2182

fixes #1206

According to the comment

// deleting duplicated foreign keys present on both on the orphanedForeignKey
// and the removedForeignKeys from changedTables

A check must be had on the $removedForeignKey so it does point on the removed table. Currently it does unset all keys removal even the one pointing on other table.

On the MySQLPlatform::getDropForeignKeySQL table name will not be escaped if the name is passed instead of the object table itself.

Since the getLocalTableName use the localTable property the object is always available, there is no reason not to use it.

fixes #1339
closes #921