Warn on invalid input

[sadrasabouri]

What does this implement/fix? Explain your changes.

There were places in menu which was formerly ignored if user gives invalid input. Some of them (listed below) are now checked before start generating graphs.

• all 0 and 1 options are now restricted to only 0 and 1
• file_name now can not be empty
• output_format should be inside the valid range
• engine should be inside the valid range
• vertices, number_of_files, min_edge, max_edge are now restricted to positive integers

Any other comments?

Checking if max_edge > min_edge or max_weight > min_weight seems to be handled in a different way. If it's necessary we should do it in another PR.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (07aace7) 98.11% compared to head (d998d81) 98.58%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #152 +/- ## ========================================== + Coverage 98.11% 98.58% +0.47% ========================================== Files 4 4 Lines 475 491 +16 Branches 74 76 +2 ========================================== + Hits 466 484 +18 + Misses 6 4 -2 Partials 3 3 ``` | [Files](https://app.codecov.io/gh/sepandhaghighi/pyrgg/pull/152?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sepand+Haghighi) | Coverage Δ | | |---|---|---| | [pyrgg/functions.py](https://app.codecov.io/gh/sepandhaghighi/pyrgg/pull/152?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sepand+Haghighi#diff-cHlyZ2cvZnVuY3Rpb25zLnB5) | `98.15% <100.00%> (+0.91%)` | :arrow_up: | | [pyrgg/params.py](https://app.codecov.io/gh/sepandhaghighi/pyrgg/pull/152?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sepand+Haghighi#diff-cHlyZ2cvcGFyYW1zLnB5) | `100.00% <ø> (ø)` | | | [pyrgg/test.py](https://app.codecov.io/gh/sepandhaghighi/pyrgg/pull/152?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sepand+Haghighi#diff-cHlyZ2cvdGVzdC5weQ==) | `0.00% <ø> (ø)` | |

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