* calendar.c: finished preparing strings for i18n

* calendar.c: finished preparing strings for i18n
* sysmsgs.c: Save/Cancel buttons now have different element names, so we
  can do a "which element has a nonzero length" check instead of a "what
  is the value of this element" check.  This is vital because the value
  equals the label, and the label will change if the language changes.
  This must be done throughout the system.