Flag layer size when given the option to download

[DrTrevorDavies]

This is a great addition and will really speed up the process when building maps 100 times when trouble shooting. I think it may be worthwhile to put 'layer file size' when given the option to download a layer. I have no idea how large they are but if they are 100 megs it may start impacting local HD space (for those of us with small SSD). Great work!

[ateucher]

This is a good idea, but the web service the layers are retrieved from don't have the capability to tell us the size... they are cached as highly compressed .rds files so even the biggest ones are pretty small (usually less than 15MB).