Remove redundancies from PATH

[Irubataru]

I quite indiscriminately add to PATH whenever I think I could need it, which means there will be a lot of repeated entries. I do not know if that is an issue, but it at the very least is a bit messy. There are quite a few ways around that:

• Have a cleanup script that removes redundancies (see this SO answer)
• From the same answer, have functions that add in a clean way
• Have ansible tasks that does this for me so I can write it in something other than bash

While on the subject maybe I should create a PATH utility for better looking at the PATH variable.