Since table grid cells are drawn with a non-bezelled border, set MBTableGridCells `bordered` to YES and `bezeled` to NO (default). This matches cell drawing with editing. The previous configuration (`bezeled` == YES) made editing be vertically offset because NSTextFieldCell was led to believe there was a bezel. Fixes #3.
Merge pull request #4 from bavarious/align

Prevents vertical offset during cell editing