remove dependencies on direnv and nix

[notmike-5]

remove dependencies on direnv and nix

[liamcottle]

Howdy. Please provide explanation why this needs to be removed. It was added in #205 Also please ensure pull requests are opened against the dev branch.

[notmike-5]

From what I can tell direnv and nix are not dependencies of MeshCore. The file .envrc is usually left to users to setup their own local environments as suits their needs. The file .envrc in the repo currently enforces the development environment of some nix/direnv users onto all users, overriding whatever particular environments users may have themselves. #205 adds .direnv/ to the .gitignore in recognition that this environment is not needed by most users. It is advisable to similarly remove .envrc from version control since the environment may need look different for every different clone of the repo.

So, my claim is that #205 should really have added .envrc and .direnv/ to gitignore.txt and left it at that. The other files are particular to the authors' development environment.