Preferences Feature added

[vinayakjeet]

Work-In-Progress: Pull Request #84

Adding "Preferences" Option to Avogadro's "Edit" Menu

This pull request introduces a significant enhancement to the usability and accessibility of the Avogadro application by adding a new "Preferences" option under the "Edit" menu. This feature enables users to easily access and modify their application preferences directly from the main interface.

Implementation Overview:

• Modifications to MainWindow Class: The implementation includes comprehensive updates to the MainWindow class, affecting the .cpp, .h, and .ui files to ensure the preferences dialog is seamlessly integrated into the application.

• Streamlined User Experience: By providing a quick access point to settings via the "Preferences" option, this addition significantly streamlines the user experience. It caters to the needs of users looking to efficiently customize their Avogadro application settings.

Expected Impact:

• Enhanced Usability: Introducing an accessible and easily navigable "Preferences" option directly in the main interface markedly enhances the overall usability of the Avogadro application.

• Improved Accessibility: This feature makes it simpler for users to tailor the application to their specific needs, thereby improving accessibility and user satisfaction.

This addition is poised to offer a more intuitive and user-friendly interface, encouraging users to explore and customize their settings to better suit their individual needs and preferences.

closes #84