I didn’t have enough time to build the project but I was able to compile it. I had problems with (#include ../) statements. I fixed this by moving all files to the same folder and get rid of (../). Also the LiquidCrystal-I2C-library that you linked didn’t compile and I used this one https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads/LiquidCrystal_V1.2.1.zip
I will probably build the proto 2 circuit tomorrow but I couldn’t figure out where you declare the I2C addresses. It would be helpful if you can post a circuit schematic.
Thank you for your effort, great job!