* DataColumn.cs: Fixed ParamName of ArgumentNullException. Modified

* DataColumn.cs: Fixed ParamName of ArgumentNullException. Modified
exception message for invalid DateTimeMode value to match MS. Code
formatting.
* DbDataPermissionAttribute.cs: In KeyRestrictionBehavior, reuse
ExceptionHelper.CheckEnumValue.
* ExceptionHelper.cs: Use same exception message for both 1.0 and 2.0.
* Index.cs: Fixed compiler warnings. Code formatting.
* SqlCommand.cs: Use ExceptionHelper.CheckEnumValue for enum checks.
* OleDbCommand.cs: Use ExceptionHelper.CheckEnumValue for enum checks.
* DBDataPermissionAttributeTest.cs: Improved test for invalid
KeyRestrictionBehavior. Fixed line endings.
* DataColumnTest.cs: No longer derive from deprecated Assertion class.
Code formatting. Added test for DateTimeMode.

svn path=/trunk/mcs/; revision=87866