Click the green flag to start/clear. Then click somewhere to place a proton. Press o to change rendering options. Press the spacebar to render the field lines. USE TURBO MODE ! ! !
Credit to "drmcw" for helping me find an internal scratch rounding error. Coming very soon: deletion, modification of protons Coming soon: electrons 06/11/2014: Basic version release. 08/11/2014: Made variables user interactable.