WL#468: Unicode Support

Add the support for all unicode APIS SQLConnectW, SQLExecDirectW, ... and soon. 

The implementation could be as follows:
- Driver must talk to server to/from through Unicode later
- And in case of ANSI calls, convert them to multi byte before sending it to
server and vice versa when returning back.
- The best way could be to have a ANSI APIs(SQLConnectA, SQLExecDirectA,..) on
top of Unicode APIs.