programview: removed dependencies on edit box

the font of the program view dock widget was set to the same font set in
the edit box, which was a fixed width font; but this was not necessary
and the default font is sufficient for the program view

the other dependency was the constant that determines the base (first)
line number to display on the program (currently set to zero during
development to match the internal line indexes) was moved from the edit
box class definition to the ibcp.h header file as a global definition