set program view font to same used by edit box
update line number display in program view dick widget

program line delegate now has base line number, one digit pixel width,
and line number area width set up in the constructor; a new function to
calculate the line number area width when the line count changed, which
emits a signal that the program view needs updating when the width
changes; and paints the line number with a gray background in its own
rectangle

in main window, program line delegate and program view needed to be set
up before loading the program so that the program view has a change to
calculate the line number area width

main window now maintains the program line count and can update the
program line delegate when the line count changes; and processes the
signal from the program line delegate when it requests the program view
to be update

the edit box base line number constant was made public to be accessible
when the program line delegate is created