Option to disable checksums

[mic159]

Unfortunately my hardware (a Benbox Laser Engraver) does not support GCODE checksums and line numbers.
I noticed that there is an option to force checksums to be always ON, but not the other way around.

Would it be possible to add an option to disable it?

I couldn't see a way to fix it with plugins, so to make it work I can change util/comm.py:1524 like this:

# now comes the part where we increase line numbers and send stuff - no turning back now
#if (gcode is not None or self._sendChecksumWithUnknownCommands) and (self.isPrinting() or self._alwaysSendChecksum):
#    linenumber = self._currentLine
#    self._addToLastLines(command)
#    self._currentLine += 1
#    self._doSendWithChecksum(command, linenumber)
#else:
self._doSendWithoutChecksum(command)

1. What were you doing?
   Pressed print on a .gcode file.
2. What did you expect to happen?
   The engraver to whirl into action.
3. What happened instead?
   The engraver sends back ok but nothing happens.
4. Branch & Commit or Version of OctoPrint:
   Version: 1.2.0-rc1-3-g46711ce-dirty (master branch)
5. Printer model & used firmware incl. version
   (if applicable - always include if unsure):
   benbox laser 2.7(c) mul 2014.12.25
6. Browser and Version of Browser, Operating
   System running Browser (if applicable - always
   include if unsure):
   Ubuntu 14.04 - Chrome
7. Link to octoprint.log on gist.github.com or pastebin.com
   (ALWAYS INCLUDE AND DO NOT TRUNCATE):
   https://gist.github.com/mic159/9ea8c2a8ff66e4c7233c
8. Link to contents of terminal tab or serial.log on
   gist.github.com or pastebin.com (if applicable - always
   include if unsure or reporting communication issues AND
   DO NOT TRUNCATE):
   https://gist.github.com/mic159/9ea8c2a8ff66e4c7233c
9. Link to contents of Javascript console in the browser
   on gist.github.com or pastebin.com or alternatively a
   screenshot (if applicable - always include if unsure
   or reporting UI issues):
   N/A
10. Screenshot(s) showing the problem (if applicable - always
    include if unsure or reporting UI issues):
    N/A

I have read the FAQ.

[foosel]

Implemented in devel branch.