Add flag to ignore file hashes

[felix920506]

Add a flag to ignore invalid file hashes.

When both --debug and --ignore-hash flags are set, invalid checksums will produce warnings but the test will continue.

[felix920506]

rebasing on top of latest develop branch

[BotBlake]

Implementation-wise this is good to go.
However it still requires UI work.

Its important to mark debug output as such.
Since you do need to reuse it a bunch of times, it might be worth defining a new constant or write a new helper function in util.py.

Also make sure that the code stays readable.
It might be clear to you that the hash_dict is gonna be filled with hash_entries which then again are filled with a type and a hash, but hiding all that behind a single letter is still not ideal.

No major changes required though. All minor UI stuff.

[BotBlake]

Main points:

• Should an end-user have access to this?
  I see two options:
  1. make it invisible in the help
  2. adjust the description to make clear its potentialy dangerous
• Make sure to use the new print_debug() in all places where manual debug styling was done before
• Dont print EVERYTHING on the terminal "just because"
• be aware of all possible situations obtain_source can be called in.

Make sure to not only test the changes on the system you had the issue on, but also on one where it never occured/ you had the files already/ the files are actually faulty/ ...
Especially here in obtain_source, a lot of different states and edgecases can happen.

[BotBlake]

lgtm