Tidy up cosmetic items

Remove obsolte ultisnips and youcompleteme configs
Add go path

Prep for trying elvish shell
Implement :Jump/:cd commands
Switch iterm profiles from shell
Manually specify $VIMRUNTIME for neovim

Neovim doesn't ship with the vim runtime, so features like syntax highlighting
trigger an error. It can use the Vim 7.4 runtime that ships with vim, however.

https://github.com/neovim/neovim/issues/601

Other changes:
* Neovim's `.nvimrc` inherits from `.vimrc`
Clean up :Marked command