Allows installation using pip (local source)

I tested that it works with both the normal install method and also pip, but only on my machine. Probably needs a few more tests on other machines.

Thanks!

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Install and uninstall catfish locally from source directory using the pip tool.

In the catfish source directory use:

pip3 install .

pip3 uninstall .

This installs (or uninstalls) catfish for the current user. Depending on your setup, pip or pip3 may be the correct command.