gladevcp -remove highlight from hal_sourceview when idle

The highlight line represents where the program is or where it will
run from. When the interpreter is not running the file the highlight
should hide, to indicate that the program will start at line 1.
gscreen -revamp restart dialog behavior and methods

Previously whith the dialog showing pressing the start button would
have linuxcnc _always_ restart at the line indicatd on the dialog.
Manually closing the dialog would set the start line back to zero.
While interesting, it is probably unintuative and of limited use.
Now the dialog is used to select the line to highlight indicating restart
position. Pressing enter or return will keep this line showing.
Pressing cancel will clear the highlight line and set restart to 0
In short the highlight line shows where linuxcnc will start. The
dialog is for placing the highlight.

In the process update_restart_line(line,reset_line) now only takes
line. Some user Handler files may need to be adjusted.
gmoccapy -fix a function call because of Gscren changes.

update_restart_line( ) doesn't take two values anymore.
More over, the premise for calling this function is not reguired
anymore - HAL_sourceview now automatically clears the highlight line
when linuxcnc's interepreter is idle.
gaxis -destroy the restart dialog if run is pressed

a little more user friendly.
docs -add links to HAL widget reference paragraph