Symlink instead of copying files

[alichtman]

    Multi-threading for reinstallation of packages.
    Multi-threading for config backup, just like is done for dot backup
    Not copying atom/sublime/vscode packages
    git clean

EDIT: symlinking would be the largest improvement by far. #188

[4ndrej]

Whole backup multithreading should be removed. Doing backup on spinning disc may also conflict with req 1 since spinning disc is not good parallel worker at all

[ShivangiSingh17]

let me try?

[alichtman]

@4ndrej Most modern computers have SSDs in them, not hard disks. In short: multithreading is a huge performance boost when you're doing a lot of data copying and it should be added here.

@Starcode71Ooze go for it, man. If you need any help, let me know.