[aliases] tweak rvm, ocaml; add nixos
[env] new opam config
[git] rework log aliases
[ocaml] add opam config
[ssh] add mirage-xen stanza
[pandoc] tweak signature, add new templates
[emacs] tweak fill modes
[git] ignore emacs and ocp droppings
[emacs] update packages: org-mode, markdown, fill-column-indicator, solarized