Print a message when printing is aborted

Messages in gcode files like “M117 Printing…” were not being cleared on
Stop Print.
Print a message when printing is aborted

Messages in gcode files like “M117 Printing…” were not being cleared on
Stop Print.
Merge branch 'lcd_abort_message' of https://github.com/thinkyhead/Marlin into lcd_abort_message
Print a message when printing is aborted

Messages in gcode files like “M117 Printing…” were not being cleared on
Stop Print.
Merge branch 'lcd_abort_message' of https://github.com/thinkyhead/Marlin into lcd_abort_message
Merge pull request #1163 from thinkyhead/lcd_abort_message

LCD "Abort" Message