UTF-16 support

I'm testing the recently committed UTF-16 support.

I believe this line in src/tds/config.c's tds_config_login() is wrong:
connection->use_utf16 = login->use_utf16;

It only ends up turning off the UTF-16 support you asked for in the configuration files, which previously got read into the "connection" structure, with a zero from the "login" structure. So the "use utf-16 = yes" line from freetds.conf gets overwritten and ignored.
Simply removing the line works, or wrapping it like all the other boolean options:
if (login->use_utf16) {
	connection->use_utf16 = login->use_utf16;
}

Then everything appears to work fine with dblib and ctlib.