Added missing SQL operators for each grammar

I've added bitwise operators using the following grid:

|        | MySQL | PgSQL | SQLite | MSSQL |
| ------ |:-----:|:-----:|:------:|:-----:|
| AND    |   &   |   &   |   &    |   &   |
| AND-E  |       |       |        |   &=  |
| OR     | (pipe)| (pipe)| (pipe) | (pipe)|
| OR-E   |       |       |        |(pipe=)|
| XOR    |   ^   |   #   |        |   ^   |
| XOR-E  |       |       |        |   ^=  |
| L-SHFT |  <<   |  <<   |   <<   |       |
| R-SHFT |  >>   |  >>   |   >>   |       |

Additionally added:

- SQLite's `==` operator,
- MSSQL's not-greater-than (`!>`), not-less-than (`!<`) operators.

I haven't added NOT (which is universally `~`) as I'm not sure how this would be used with `where($col, $op, $val)`.