remove a useless escape in front of the tests print
bugfix: correct host display switch and corresponding unit tests
use escape h as hostname
Add the `lptag` function to add a prefix

Note: the `lptag` function is  convenient way to add a prefix. You can thus add
a keyword to your different terminals:

    [:~/code/liquidprompt] develop ± lptag mycode
    mycode [:~/code/liquidprompt] develop ±
Merge branch 'develop'
Display colored brackets in a term multiplexer

A pair of square brackets, colored in blue if your current shell is running in a
terminal multiplexer (screen or tmux).