MenuField: need stdio.h if TRACE enabled

* Also update authors adding myself
Revert "don't open the menu if it's disabled."

This reverts commit ce8253d97b588366540230d11fb534c4846d0a09.
MenuField: enable/disable the menu field when...

the child menu bar or the child menu bar's menu is enabled/disabled.

This means that there is just one status we have to check, the menu
fields, and the child menus agree. This change takes practical form
in the Backgrounds preflet which disables the placement menu when
the image is set to "None", but, only the menu got disabled and not the
parent menu field so the label was erroneously still drawn as enabled.
MenuField: Open the menu bar when the label is clicked

Fixes #6894

Private DrawLabel() method renamed to _DrawLabel() and rest of drawing
code moved to new private method _DrawMenuField(). These methods both
check to make sure that they are drawing in a valid rect that intersects
updateRect.

When label or menu is selected Draw a the label background in the selected
menu color matching the behavior of BeOS R5.

_DrawLabel() calls be_control_look->DrawLabel()

Update copyright year in MenuField.h