Add '--no-color' flag to 'pretty' command

[khos2ow]

Prerequisites

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• This pull request fixes a bug.
• This pull request adds a feature.
• This pull request enhances existing functionality.
• This pull request introduces breaking change.

For more information, see the Contributing Guide.

Description

This PR adds a new --no-color flag to pretty command. Using this flag results into a color-less output in the terminal, note that the output is completely plain text and color less and not using \033[0m (reset color character).

Issues Resolved

Fixes #78

Checklist

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• I have read the Contributing Guidelines.

Tests

• I have added tests to cover my changes.
• All tests pass when I run make test.

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Code Style

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