Move SMARTS patterns to a .csv file

[Aariq]

This closes #112 by moving the SMARTS patterns previously defined in get_fx_groups.R into a .csv file in data-raw/. This csv file is used to build a user-facing data set and add a named vector of SMARTS patterns to the package internal data for use in get_fx_groups().

The user-facing data.frame, smarts_simpol1 documents the column name in the output of get_fx_groups(), SMARTS pattern (if applicable), the function or calculation used to count the functional group, and any notes about how counts are corrected or what the pattern captures.

The internal dataset, smarts_patterns_simpol1 replaces all the SMARTS patterns defined in get_fx_groups().

[Aariq]

devtools::check() passes on my mac, so probably safe to ignore failing check