Separate out SS_Query and MySQLQuery from their Database classes

Coding conventions state one class per file (unless it uses an _ to indicate related classes.
Merge pull request #2688 from wilr/spiltclasses

Separate out SS_Query and MySQLQuery from their Database classes
Update form.md

Under the heading ...THE FORM....
 Instantiating a form....
$controller..
  replace and to an.
Merge pull request #2690 from sanjaymundhra/patch-1

Update form.md