Lees-Edwards BC

Hi Josh!

I have spent a good part of the day to merge the LE-BC with the master branch. Now the code does compile. I haven't tested whether it runs, though.

There were two more significant issues in your code. Therefore, so far, I haven't merged your code into the master branch, as we would like to see some modifications before we want to do that.

First of all, I noticed that you have modified "src/myconfig-default.hpp". Please **never** touch that file! It defines what features are activated in the code *by default*. If I had not noticed that you had changed it, all other users would by default have Lees-Edwards-BC activated in their code, which is probably not a good idea. Simply put a file "myconfig.hpp" into the build or source dir, and you are fine.

Second, there is some problem with your redefinitions of the functions "distance", "distance2" and "distance2vec" in "grid.hpp". Meanwhile, we have moved these functions into "utils.hpp", where in principle the box size etc. is not even known. These functions should compute the Euclidean distance no matter what. The correct way to do what you want is by the modification of the "get_mi_vector" function, because that may depend on the BCs.
We noticed that we will have to discuss the matter somewhat more, so we will give you more information in the next days.

Olaf