* SqlCommand.cs: Fixed param name in ArgumentException for negative

* SqlCommand.cs: Fixed param name in ArgumentException for negative
CommandTimeout to match MS. On 2.0 profile, throw NRE in Prepare
when connection is NULL. In Prepare, return immediately after
connection check (2.0 only) for stored procedures, or when no
parameters are added. Added check to see if transaction is
associated with same connection as the command and updated
exception messages.
* SqlCommandTest.cs: Enabled CommandTimeout test. Enabled test for
Prepare with NULL connection. Enabled test for bug #412586.
* SqlCommandTest.cs: Enabled and improved tests for pending transaction
and transaction that is not associated with connection. Added tests for
Prepare.

svn path=/trunk/mcs/; revision=109058