Support for config files that differ for copies of the same file/symlink

[nightlark]

In #216, one of the potential issues with only running once on a file is: Some plugins might need to gather information from other files relative to the one they are looking at (based on symlink location).

Two questions for addressing this issue are:

• Should an extra optional argument be added to the info extractor hook to tell the plugin if a file with the same hash has previously been seen, so it can adjust its behavior accordingly?
• Should a separate info extraction hook be added for duplicate files in different locations?

Thinking about this a bit more, possibly the best solution would be some changes to go with refactoring the internal Surfactant representation of gathered data to use a graph. With this option, an infoextractor plugin would gather data from the extra files as their own separate software entries, and then the relationship establishing plugins would use info from those files as needed based on the install path being considered. This would allow more accurate relationships to be established in situations where the config file that goes with an executable has different settings for binaries that are identical but live in different locations.