for simple structures, drop the (1), (2), (3) notation

[computron]

(py37) computron-7:~ ajain$ robocrys mp-1960
Adding oxidation states...
Li2O is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Li(1)1+ is bonded to four equivalent O(1)2- atoms to form a mixture of corner and edge-sharing LiO4 tetrahedra. There are one shorter (2.01 Å) and three longer (2.02 Å) Li(1)–O(1) bond lengths. O(1)2- is bonded in a body-centered cubic geometry to eight equivalent Li(1)1+ atoms.

Here, there is only a single Li and O, so no need to label it as Li(1) or O(1).

[utf]

This is controllable by the --no-symmetry-labels option.

Based on the discussion in #6, it seems like a good idea to have an option to automatically adjust the verbosity parameters based on the description length.