R1953 patch: UI improvement: buttons

- Use PointingHandCursor as the default cursor for component buttons.

- Replace the QPushButton with CustomButton in Function and Serial Port .

- Buttons in the Function component are checkable, but I can't find any meaningful code that make use of their checkstate. It seems that these button codes are copied from the swtichdip, so I did some cleanup.

Thank you.
Patch applied at Rev 1954.