Swap master now swaps the master window with the prior master window if
swapMaster is called while the master window is focused.

Change the Marking to use XMonad's extensible state rather than
hand-rolling it myself. Allowed me to delete the XPlus monad.

Finally removed the buggy hjkl navigation in favor of a more traditional
key bindings:

  - h,l move between windows like Tab and S-Tab
  - j,k adjust the master window size

Added ability to swap current window with a marked window using
S-'-<mark>.

Have an install script to install XMonad-jrahm on the expected platform.