Adds VesselView

This adds the the 3D vessel viewer that is supported by RasterPropMonitor.

The upstream version has three installation packages, one that supports Raster Prop Monitor, one that supports only Blizzy's toolbar, and one that supports both. The last one merely contained the union of the files in the two previous.

Therefore I have split this into three packages, the first one containing the files shared by all three upstream versions, depending on a virtual package provided by the other two, ensureing that at least one is installed. The other two contain the files specific to one of the uncombined versions. Installing them both is equivlent to installing the complete package. 

This is not a NetKAN file because the GitHub repo does not contain the compiled packages, and it is not uploaded to any other host for which NetKan has special support.

I'm mentioning @PeteTimesSix, here so he has the chance to comment on or object to the packaging. However, he does not seem to be active on the forums or GitHub, so I'm uncertain if we will hear back from him.

The package was built against 0.24.2, but nobody has reported any issues with using it in 0.25.0, so that is included as a supported release here.