OSx considerations for Tmux, ssh fixes, and more.

- Broke out a new file only loaded on OSX systems.
-- Launches the shell in the user namespace so clipboard works.
- Reorganized a bit, cleaned up some dead code, more comments
- Added a couple of lines that should ensure proper user@host when ssh'd
- Display pane's own titles (what xterm would display) in tmux's tabs
- Changed flip/flop key to tab instead of just mashing C-a
- Double tapping C-a now passes the prefix to the pane process
- Enabled vim style pane and copy-mode movement and selection/copy/paste
- Disabled delay when swapping tabs due to expected key-repeat
- Prefix+Escape now enters copy mode like Screen
Vim window title, clipboard, glyphs, docs, colors

- Enable Airline's tabline extension
- Dump in the old Powerline glyphs as comments
-- Mostly so I can look them up in the git history later
- Set up fonts for both OSX and Linux
-- This can be DRY'd up later
-- Added my new hotness favorite font to the top (Meslo)
- Found out how CSPrrox's attr_map works
-- Enabled italic and fg translation
-- Enable CSApprove for all modern vims
-- Need to test this with older vims
- Removed a conditional that broke vim's clipboard in tmux
- Added a nice Window Title for tmux/*term
- Documented the hell out of the titlestring
ZSH looks for different user-setup directories.

- It just feels wrong without a shebang line.
- Autodiscover the user-setup directory because I never remember if it
  should be a dash or an underscore.
The things I always forget on OSX.
Ignore tags and untidy submodules.