[Irwin1985]

I added tests for the menu functions (BAR, PAD, POPUP, MENU, MRKBAR, MRKPAD, PRMBAR, PRMPAD) using menus built with the DEFINE commands, and compared the results with VFP 9.

While writing them I found a few problems, so they're fixed here as well:

• The plain forms of DEFINE POPUP, DEFINE BAR, DEFINE PAD, DEFINE MENU and ACTIVATE POPUP weren't expanded by the header, and ON SELECTION ... DO proc didn't compile.
• RELEASE MENUS and RELEASE POPUPS with a list of names didn't compile either.
• PRMBAR() and MRKBAR() used the position of the bar instead of its number, so separators and gaps in the numbering gave the wrong bar. BAR() now returns the number too.
• PRMBAR() and PRMPAD() return the prompt without the < marker.
• Menu, popup and pad names are no longer case sensitive.
• RELEASE MENUS left the menu registered.
• PAD() and MENU() came back empty when the bar was selected without opening the menu first.

Unknown names still return an empty string or .F. instead of raising an error like VFP does. That's how the existing tests expect it, so I left it that way.