* DataGridView.cs: Implemented AutoResizeColumn(s).

* DataGridView.cs: Implemented AutoResizeColumn(s).
* DataGridViewCellStyle.cs: Added SetAlignment, fills in a StringFormat
  according to the Alignment.
* DataGridViewColumnHeaderCell.cs, DataGridViewTextBoxCell.cs:
  Implement alignment and padding when painting.
* DataGridViewRow.cs: SetValues: Don't create a cell if it already
  exists.
* DataGridViewCell.cs: Implement BorderWidths in the most primitive
  way.
* DataGridViewColumnCollection.cs: Raise OnColumnAdded on the DGV when
  a column is added.

svn path=/trunk/mcs/; revision=83189