Separate value and buffer in stmt.bindParameter

Fix prm->GetBytesInBuffer (wrong number if indicator exceeds buffer
length)
Better error messages
stmt.moreResults stub
Add stmt.moreResults
Begin fixing Parameter::Marshal

For bound input/output parameters, the bound input buffer is not being
filled (seems like it is for primitive types now, but need
SQL_CHAR/SQL_WCHAR/SQL_BINARY)