Create a default tmux session only when none defined in tmux.conf

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Support $PYTHONUSERBASE per PEP 370

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Enable relocation of Prezto

Out-of-the-box Prezto requires all files to be located in ~/.zprezto or
$ZDOTDIR/.zprezto.

To make it possible to initialise Prezto when it's elsewhere I've added
support overriding the location of Prezto via the ZPREZTO_DIR
environment variable.
Modify ZSH initialisation

- Add ~/.dotfiles/bin to path
- Source an env.zsh file in priv
- Load Prezto from my custom location (~/.dotfiles/zsh/init.zsh)
- Export paths related to ZSH initialisation
Add my utility functions
Add my custom prompt
Add my modules
Add my preferred git aliases
Add my aliases to utility module
Use console vim everywhere
Bring back hub and git-extras
Initialise dotfiles functions in zshrc
Bring back gl and gp aliases
Remove `rm` -> `rm -i` alias
Alias fs -> foreman start
Enable tmux module
Stop using difftest be default
Add Homebrew NPM to path if present
Stop printing juvenile messages on logout
Back to GUI Vim