Non portable functions are called with __function_$OS. This way you
don't have to call "uname" at each prompt.
Currently ported functions :
- __load | Linux, FreeBSD | detect current system load
- __cpunum | Linux, FreeBSD | number of cpu
* less punctuation: replace brackets with a single letter around battery, load, nothing around jobs and return value
* avoid extra spaces
* uncolored punctuation
* color the prompt mark in red if root, else in bold white
* user in light white and working dir in bold white
* modular function for building the prompt from the othe functions
* use tput for colors, everywhere
* show the standing commit numbers
* support branches without remote
* check if a battery is present
* show error codes of previous commands
* use ± as the prompt mark within git directories
* somewhat different colors
