Add DOIs to proceedings and collections

SPIE papers come with DOIs and ADS includes them in entries.
It seems odd to me that we include DOIs for articles but not
for proceedings papers that have them. SPIE papers are notoriously
hard to parse since page numbers are usually missing
from references.

bst/aasjournal.bst

@@ -1285,6 +1285,7 @@ FUNCTION {incollection}
 %    }
 %  if$
   format.pages "pages" output.check
+  format.pid
   format.url output
   fin.entry
 }
@@ -1313,6 +1314,7 @@ FUNCTION {inproceedings}
 %    }
 %  if$
   format.pages output
+  format.pid
   format.url output
   fin.entry
 }