[Gm2] latest git push to master branch

[Gaius Mulley]

Hi,

some bug fixes to the master branch now improve the accuracy of error
reporting.  For example here are some errors detected by the whole
number overflow plugin.

mult3.mod:11:11: error: runtime error will occur, whole value multiplication 
will cause a range overflow (in _M2_mult3_init)

   11 |    r := x * y ;
      |           ^
overflowdiv1.mod:12:11: error: runtime error will occur, whole value ceil 
division will cause a range overflow (in _M2_overflowdiv1_init)

   12 |    u := x DIV y ;  (* compiler should detect DIV causes overflow rather 
than assignment.  *)
      |           ^~~
t.mod:7:10: error: runtime error will occur, whole value addition will cause a 
range overflow (in _M2_t_init)

    7 |    j := i+1
      |          ^


regards,
Gaius