* Added the back button to the main Ui
* Changed the naviation in the reader ui so that when the next or previous chapter links are clicked, instead of adding the a new history entry, it will replace the current History entry and rereder the Reader component
* - Made changes so that if history is of length 1 then the backbutton will take you to /library
- made use of the startsWith method so that if we use url for the saving the last viewed category there won't be a need to change this
- changed a few relative imports to absolute imports
* Back button won't show for any route that has an icon in the sidebar
* fixed the navbar color when in lightmode
* Used the grey options available in the Theme object
- Added the package-lock.json
* removed package-lock.json
* Changed the colors in the navabr to the closest available color in the Theme object in Material UI
* Made the sidebar close button available even the staticNavbar setting is set to true
* reverted the changes to the .gitignore
