FileNotFoundException for ProjectReference which has not yet been built

[Robert Schmidt]

Thanks for a very convenient tool!

I encountered problems with project references. StrongNamer would fail with FileNotFoundException if the referenced project had not yet been built. The errors showed up in the VS Errors window.

This in turn caused VS Intellisense (or maybe Resharper - not sure) to claim that no symbols where available for the referencing project - lots of red squiggles everywhere.

A workaround was to build the solution, close it and reopen, which seemed to "reboot" the Intellisense information. But the errors would sporadically reappear during development, when StrongNamer again encountered an unbuilt ProjectReference.

I'll make a PR for a fix.