Superpose3d

This is the first version of the software where I remembered to click on the "Draft a Release" button.

Updated to the newest version of the "lambda_lanczos" submodule.
This should make it cleaner and easier for everybody who uses this library because now they can simply copy all of the header files from "include/" and "lambda_lanczos/include/" into the *same directory*. When they wish to compile your code, then set your include path to include *that* directory.

*(Previously it was necessary to mention the name of the subdirectory where the lambda_lanczos.hpp header files were located ie. "lambda_lanczos/lambad_lanczos.hpp".)*

This version of superpose3d.hpp passes all tests, but I have yet to test it for memory leaks. I'll try running valgrind on it soon.