Sonar Core is the modding framework as part of Calculator and now Practical Logistics. It features a number of useful Java classes which allow me to work much quicker on adding new stuff. It is currently only used by me, but the source code is still open. Sonar Core has been split from Calculator to allow for the release of Practical Logistics.
Decorative Blocks: In Minecraft 1.8.9 and up Sonar Core comes with some decorative blocks you may recognise from Calculator.
For 1.9.4 and 1.10.2