adding support for LONGINT in SqlDrivers.Table. Refs: #87. As proposed by manumart1, 2015-11-15, see http://community.blackboxframework.org/viewtopic.php?f=16&t=109#p555 ReadLong uses string conversion because there is no WinSql.SQL_C_SBIGINT;
Signed-off-by: Josef Templ <josef.templ@gmail.com>
Josef Templ