MySql platform getAlterTableSQL does not quote existing column names

When creating alter table SQL, the MySqlPlatform class does not quote names for columns of an existing table when building a CHANGE query. This can cause SQL errors.

It creates queries like this:

ALTER TABLE my_table CHANGE key `key` INTVARCHAR(255) DEFAULT '' NOT NULL';

Attached is a patch to fix this.

As an aside, is this the best way to contribute a patch? Or is a GitHub pull request better?