New icon set and color picker

We have freshened things up a bit. The icon set and a color picker in the tool have both been updated. The icons are the same but they look much more current en fresh. The new color picker contains fewer colors but they are much clearer and more distinctive.

We also updated the icons used in the right-click menus and the icon that is being used for the subgroups. 

We started work on Tom's Planner almost 10 years ago and it has been available to our users for almost 8 years now. During these years the general look & feel of online software changed quite a bit. To stay current and to avoid looking outdated we must keep up. 

Tom's Planner is here to stay for many decades to come. Gantt charts have been around for more than 100 years. We are aiming to do exactly the same!!