Improve test coverage

[sveetch]

Is your feature request related to a problem? Please describe.

Project is well covered in tests but some options are not properly covered.

Describe the solution you'd like

We should add some more tests to consolidate behaviors.

• [x] Missing test for diskette_dump --no-archive;
• [x] Missing test for some options in load handler;
• [x] Missing test for some options in dump handler;

[sveetch]

Done in v0.3.2-pre.3