Diagnostics with #includes

[Danp2]

One minor issue I see is that if there are problems related to an include file, the diagnostics for the include file remain visible even after the main au3 file is closed.

Another issue -- If you fix the problem in Test.au3, the Statement cannot be just an expression. error shown in the Problem tab doesn't get removed. I'm sure this is because the diagnosticCollection isn't automatically cleared because there is still an error in the included file.

Originally posted by @Danp2 in #158 (comment)