Ship OSD icons separately

[seriyps]

In this commit OSD icons were embedded into the source code. I don't think it was the right decision, because it limits customization.
gehee/FPVue_rk@7ab9e11

Also, might be nice to think about some ways to customize the OSD somewhat more than it is possible now. Maybe introduce some ways to define OSD elements declaratively in a file?

[widgetii]

It's a perfect idea.

[luastoned]

I thought about OSD elements being defined by some configuration as well.
Maybe even pull stats from a stream/different file so noone has to touch the source code to add new blocks..

[seriyps]

Created a separate ticket to discuss flexible OSD #27

[seriyps]

It is partially handled in #36 , but we need to improve our build system so it generates some kind of archive or .deb that will include binary and icons.