Add icon in Layers panel

[dericke]

Since this plugin adds a layer, there should be an icon in the layers panel, with the other layer types. There should also be a menu entry in the Add Layer menu.

[minorua]

I feel duplicate plugin menu items (in both web menu and layer menu) will not be favored. Please use Move plugin to Layer menu/toolbar option. (There is no description about the option in README now. I will add it)

Adding layer icon is nice idea.

[dericke]

Never noticed that option before. Thanks!