Expose more arguments via web app

[Robinlovelace]

• -d, --distances ...

##             The distances between concentric rings. `triangular_sequence` is useful to generate these distances
##             [default: 1.0,3.0,6.0,10.0,15.0]

• -s, --num-segments

##             The number of radial segments. Defaults to 12, like the hours on a clock [default: 12]
## 

• -v, --num-vertices-arc

##             The number of vertices per arc. Higher values approximate a circle more accurately [default: 10]
## 

• -p, --precision

##             The number of decimal places in the resulting output GeoJSON files. Set to 6 by default. Larger numbers mean
##             more precision, but larger file sizes [default: 6]