Support namespaces / modules in bif. Checkpoint.

(now actually commiting all the files)

This change is actually two-fold:
a) bif's now accept module XYZ; statements and module::ID for
   function, const, event, enum, etc. declartation
b) Added C++-namespaces to variables, functions, etc. that are declared
   in bif but accessed from C++
   This required some (lightweight) re-factoring of the C++ codes.
   Note, event's don't have their own C++ namespace yet, since this
   would require a rather huge re-factoring.

Compiles and passes test suite.
New namespace feature not tested yet.
Documentation to follow.

src/Ident.h

@@ -16,7 +16,7 @@ public:
 	virtual void DeliverStream(int length, const u_char* data, bool is_orig);
 	virtual int RewritingTrace()
 		{
-		return rewriting_ident_trace ||
+		return BifConst::rewriting_ident_trace ||
 			TCP_ApplicationAnalyzer::RewritingTrace();
 		}