Update Code For Three Dollar EC PPM Meter for Arduino

This code is a slight update of the last one, updated: This code is a slight update of the last one, updated: -Better Uptime Counter -LCD Shield -New Pin out Diagram -Restart Protected Calibration Details -EU and US Plug Calibrated Probe Also a quick update to the code so the calibration value will survive a power cut, we are storing the cell constant K [a float] in EEPROM as a scaled int, so there may be a slight change in the value following a reboot [but that small it wont make much difference]. For Code See: www.MichaelRatcliffe.com/projects or look at the project LOG at either Element14 or HAD: http://www.element14.com/community/community/design-challenges/vertical-farming/blog/2015/09/19/automated-green-house-blog101--update-code-for-three-dollar-ec-ppm-meter-for-mcu https://hackaday.io/project/7008-fly-wars-a-hackers-solution-to-world-hunger/log/25459-update-code-for-three-dollar-ec-ppm-meter-for-mcu