add README.md
initial files
it works
add missing #include
updates
various fixes

- rename to Resolution
- set parent
- change to replace whole hierarchy, root and all so as to simplify things
provide a get_resolutions()

Then you pick the ith resolution out easily.

Also go back to using radius to define resolution as the scaling isn't so important any more and the units make sense.
use inverse average radius
use log-based comparison when searching

this makes more sense as it is the inverse of distance
restructure selection to prepare for State
make it clear the relationship between the other rep particles and this
add State decorator
add multistate example
add state support to selection
add another issue to close