Extend MSSQLServer compatibility mode

[sjednac]

A while back, I've implemented some changes, that extended SQL Server compatibility mode for my integration testing purposes.

I've considered it a "hack" at the time, but it seems that more people have similar requirements. I would like to propose adding the following to the official release:

1. Discarding "table hints" in MSSQLServer compatibility mode.
2. Treating IDENTITY as auto_increment in MSSQLServer compatibility mode.

What do you think? I'll gladly create a pull request for the current version, if there would be any interest.

[grandinj]

fine by me