Stop pipes connecting to front of Heat Generator.
Prevents Mechanical Pipes connecting to the front (energy output) side of the Heat Generator.
Currently they physically connect, leading you to assume they are
transferring the lava, however they are not as this is the energy output
side and it does not accept lava.
Merge pull request #1639 from jstockwin/heatGeneratorFix

Stop pipes connecting to front of Heat Generator.