Adds a way to customize the color of the svg before download.
How to:
Find the icon you want to download
Click the 'find' icon
On the top right there should be a new 'Custom color' button. When clicked a prompt will appear where you can enter a 3 or 6 char hex code (e.g 'FFFFFF').
After clicking OK the new color should be reflected in the little color preview box. (Note that the icon itself can't be updated)
When you now click on the "Download colored SVG" it should prompt you to download the SVG, with the new color reflected in the file name.
Please let me know if you find any bugs or if you have any suggestions.
