Add option to ignore symlinks

[jelabarre59]

Is your feature request related to a problem? Please describe.
When searching for duplicates, if there are symlinks that could end up in recursive references, Dupeguru will just continue looping throught symlinks endlessly and never complete gathering files to check.

Describe the solution you'd like
Dupeguru needs an option to ignore/not follow symlinks

Describe alternatives you've considered
No such setting exists in the program. If I do not need to keep the symlinks intact in the directories being compared, I will do a find for them and delete them. However, if I need to keep the symlinks intact for some of the directories, I cannot di this, and then I cannot do the scan because it will never complete.