Calibration and Homing Improvements about farmbot-arduino-firmware

[roryaronson]

@TimEvWw I just tested this out with a new Genesis v1.5 bot. Here are my notes:

• Let's say my bot is at position (100, 100, -100). Then I tell it to FIND HOME Y. The bot will move the y-axis towards the home position and touch it, then it backs off 10mm AND sends the other axes to 0. Once it is at (0, 10, 0), it moves just the y-axis to touch the home position and back up several more cycles. So the problem here is the other axes moving to 0 mid-home-command.
• Starting at (100, 100, -100) and pressing FIND HOME Z, it touches the home Z position, then instead of backing up 10mm it continues ramming into the home position for a brief moment. Then it zeroes the other axes (the issue in bullet point 1). Then it finishes the homing cycle, but again without ever backing off the home position, only ramming it.
• If I move the y-axis to 300, then press FIND HOME Y, then the bot begins to move towards the home position. If I hand-stall the bot at say, 250 (a false home position), then it backs up a bit and then continues again towards home, expecting to find the home position at 250, but it won't because I took my hand away. Now I hand-stall it at 200. It does the same little cycle. Then I stall it again at 100 and it thinks that it has found the final home position, even though all of the stalls were false home positions. Instead, the bot should have reset the number of attempts it will make after the false home positions were not reached in subsequent attempts. See Steps 3 and 4b in the issue description.
• Calibration isn't using the touch-the-axis-end-multiple-times routine at the axis-max positions, and it doesn't do the back up 10mm part when it finds the axis-home position (it just touches the home and then rams into it a bit more)