add font option & implement toggle side panel

[eefahd]

1- Add the option to change the font style.
2- Implement toggle side panel function.
3- Fix Arabic file names problem.

[muayyad-alsadi]

thank you for your contribution, I'll merge this pull request ASAP.

although it does not alight with my vision to the UI.
I want less buttons in the toolbar and more buttons in the burger menu.

when I have time, I'll merge this and move the actions to the burger menu after the merge.

[eefahd]

Hi Muayyad,
Thank you for your reply.
I agree with you, the toolbar should be clean and have only the options that users always use like page navigation. So, I did not add any item to the toolbar, I only added the font style changing option in the burger menu.

Regards.