Refactor FilterDependencies to use LINQ groups

[Shivansps]

This is more clear to read, it also finishes adding "<=" support if it is set externally(it is for some mods on the nebula db), ill not add support for it in the UI because to make it work properly for every case it would need a complete rewrite the dependency system.

Knet 2.0 will need a complete re-write of the dependency system.

[Shivansps]

I see no point in merging this now that the dependency system will be changed sooner rather than later.