CLI Restructure

[andydevs]

• Grouped options in help string.
• Create --algorithms option to list algorithms
• Change short names for options to fit with the long name
• Rename "mbrot" algorithm to "mandelbrot"
• Update tests accordingly

New help string:

$ fractool [options]

Available Options:

Help:
  -h [ --help ]                     Produce help message
  -C [ --colormaps ]                List colormaps
  -A [ --algorithms ]               List algorithms

Algorithm:
  -a [ --algorithm ] algo           Use algorithm (see --algorithms)
  -p [ --parameter ] param=value    Set parameter. Set this option multiple 
                                    times to set multiple parameters

Image:
  -c [ --colormap ] cmap            Use colormap (see --colormaps)
  -i [ --image-size ] width,height  Set image size

Algorithms:

Algorithms list:

        - julia
        - mandelbrot

Colormaps:

Colormaps list:

        - blue2red
        - flower
        - ink
        - red2blue