patterns/bson: Support for multiple documents per file (#156)

* BSON support multiple documents per file

BSON files can contain consecutive documents glued one after another. An example of these is MongoDB FTDC metrics export.

[`bsondump`](https://github.com/mongodb/mongo-tools/blob/master/bsondump/bsondump.go) can unpack this type of BSON documents.

* Add accidentally deleted lines

patterns/bson.hexpat

@@ -3,6 +3,7 @@
 
 #pragma MIME application/bson
 
+#include <std/mem.pat>
 #include <type/time.pat>
 
 enum Type : u8 {
@@ -128,4 +129,4 @@ struct Document {
     padding[1];
 };
 
-Document document @ 0x00;
+Document documents[while(!std::mem::eof())] @ 0x00 [[inline]];