standardize regexps for code signatures

Right now the code signature regexp are basically all words separated by `.` Since `.` matches anything, this could lead to false positives, e.g. the regexp `com.here` would match `com.here` and `comehere`. Code signature printing methods generally use either `.` or `/` as the separator, so using `[/.]` would be the most accurate. Otherwise if there are other potential chars used as separators, using `\W` ("non-word chars") would be better than `.`