[prezto] Added functions to switch between prompts configurations
[prezto] Added functions to switch between prompts configurations

It is easier to use than the solution before (which required me to hack
my zshrc each time I wanted to change my prompt) and give me all the
power that I want to keep a terminal smooth and fast and get features
when I desire.

jpigree/manarch,jpigree/manarch,jpigree/config