- Added Pie Menus to Menu.c.
  - Autoselect does not apply to pie menus.

- Changed f.beep, f.circledown, f.circleup, f.continue, f.focus,
  f.iconify, and f.lower from IsFunction to IsQuitFunction. (globals.c)

- Changed conditions of assignment of IsImmFunction -vs- IsUwmFunction
  to menu functions, so that you can have functions in menus
  that act on the windows the menu was invoked in. (gram.y)

- Changed handling of IsImmFunction in Menu.c to pass function
  "window" (the window in which the menu was invoked), instead of
  "sub_window". (Menu.c)

- Made submenus pop up at the location of the mouse up event that
  selected them. (Menu.c)

- Took into account MBorderWidth when calculating menu placement. (Menu.c)

- Removed check for equality of key mask for button up event during
  menu selection. (Menu.c)

- Made all calls to exit() go through Exit() in uwm.c, so as to
  facilitate forth hacks. (Error.c, uwm.c)

- Changed GetButton.c to allow ^H as well as DELETE, and ^X as well as
  ^U, when typing at icons. Fixed bug with zeroing out icon_str.

Added global variables:
  - PieCursor
  - MenuRadius
  - PieMenus

Added defaults to uwm.h:
  - DEF_MENU_RADIUS
  - DEF_PIE_MENUS

Added fields to structures:
  - MenuInfo
    - name_x
    - name_y
    - piemenu
    - items
    - initial_angle
    - radius
    - center_x
    - center_y
    - width
  - MenuLine
    - x_offset
    - y_offset
    - quadrand
    - slope
  - YYSTYPE (y.tab.h)
    - coval

Added to .uwmrc grammar:
  - Numeric variable menuradius, that is the default radius.
  - Added "pulldownmenus" and "piemenus" flags, which set the default
    menu type, that you get with "menu".
  - Added "pulldownmenu" and "piemenu" declarations, which function
    just like "menu", but override the default menu type.
  - Added <initial_angle, radius> specification to menu grammar. If left
    out, the defaults are assumed. They are used right before the "{"
    that starts a menu declaration. They set the angle of first menu
    item, and the menu radius. They are both integers. The angle is in
    degrees.