Modify xmonad.hs to work well with XFCE4

- Add xfce4-terminal to preferred terminals.
- Avoid struts + have hotkey to toggle them avoided/not avoidied (gives the
    effect, unless on desktop, of showing/hiding the panels)
Rename xmodmap to Xmodmap so it will be automatically picked up
Add syntax, tabbing, and navigation settings to vimrc
vim - Add pathogen to manage plugins

This should probably be a submodule, but is currently just added as a file
vimrc - Add tab display and highlight trailing whitespace
vimrc - add highlighting to lines over 80 and 120 lines

Highlights in yellow when over 80 characters as a warning for coursework, and
highlights in red when over 120 characters as a warning for real development.
Yellow highlight might be annoying when working on non-coursework projects, but
I'll see how it goes.