UI improvements and using Font Icons instead of pure images

In this update the focus was on improving the user interface and replacing .jpg and .png images with Font Icons using ikonli-javafx.

Also reduced image sizes , improved application speed , added a beautiful donate button and about button on the top bar.

Way lot of features are coming , though i have University exams and dunno when i implement them all ... :(

!!!!!!!!!!!!!!!!!!Enjoy!!!!!!!!!!!!!!!

<br>* Generally UI improvements                     
<br>* Reworked players simple and advanced mode     
<br>* Reworked libraries information window         
<br>* Redesigned bottom and top bars               
<br>* Replacing actual images with FontIcons