Merge pull request #1 from Ultimaker/master

Upgrade to present UM level
temporary save machine settings (re-issued)

saves all machine settings which can be modified by M-commands to one of
ten available temporary spaces:
M605 Sn for saving in space no. n
M606 Sn for recalling from space no. n
S0 is used if S is omitted
Merge pull request #49 from Dim3nsioneer/temporary-save-machine-settings

M605 & M606
Disable I2C and SPI in electronics testing mode so those pins can be controlled with normal IO action.
Merge branch 'master' of github.com:Ultimaker/SecretMarlin
Allow to override the amount of extruders from the commandline.
Fix bug where endstop error was detected for X/Y but reported for Z.
Remove the jittering effect when the print is finished and the printer is cooling down and has a temperature around the "save" point.
Add some more checks in the time estimate code. Hopefully fixing some problems with it.
Also shown an error when no file is opened anymore during printing.
Add UPET
Merge branch 'master' into i2c_refactor
Update to I2C refactoring branch, make better use of the new I2C driver.