Changes to Omnicalc for OS 2.53 compatibility:
 - Virtual Calc disabled if the unit has bad RAM
 - RAM Recovery disabled if the unit has bad RAM
 - Version displayed is 2.26 BE if the unit has no or defective extra RAM,
   2.26 MP otherwise
 - Entries Menu disabled if OS >= 2.53 installed
 - Parentheses Assistant disabled if MathPrint is active
 - Token Showing disabled on homescreen if MathPrint is active
 - Partial line clearing disabled if MathPrint is active
 - Custom fonts now work in more places, such as on the graph screen :)
   (This writes the font data to 0FE78h.  I figure the OS seldom touches that.)

Bugs I know about that Omnicalc has in OS 2.53 (marked + if fixed):
 - First, note that 2.53 is very unstable even without the help of assembly
   programs.
 - On+n doesn't work in the Catalog.  Therefore, the custom menu doesn't work.
+/- Entries menu is very broken
+/- Token show is glitchy if MathPrint is enabled.
 - It is unknown if MathPrint is safe to use with RAM Recover and Virtual Calc.
   For now, the features are enabled.  Please report your experiences.
 - It is unknown if Fast Apps is safe to use MathPrint enabled.  Whether the
   unit has bad RAM may also affect whether this is safe. 
 - The Omnicalc PRGM menu doesn't work in the program editor.