Infrastructure for modularizing protocol analyzers.

There's now a new directory "src/protocols/", and the plan is for each
protocol analyzer to eventually have its own subdirectory in there
that contains everything it defines (C++/pac/bif). The infrastructure
to make that happen is in place, and two analyzers have been
converted to the new model, HTTP and SSL; there's no further
HTTP/SSL-specific code anywhere else in the core anymore (I believe :-)

Further changes:

    - -N lists available plugins, -NN lists more details on what these
      plugins provide (analyzers, bif elements). (The latter does not
      work for analyzers that haven't been converted yet).

    - *.bif.bro files now go into scripts/base/bif/; and
      scripts/base/bif/plugins/ for bif files provided by plugins.

    - I've factored out the bifcl/binpac CMake magic from
      src/CMakeLists.txt to cmake/{BifCl,Binpac}

    - There's a new cmake/BroPlugin that contains magic to allow
      plugins to have a simple CMakeLists.txt. The hope is that
      eventually the same CMakeLists.txt can be used for compiling a
      plugin either statically or dynamically.

    - bifcl has a new option -c that changes the code it generates so
      that it can be used with a plugin.

TODOs:
    - "make install" is probably broken.
    - Broxygen is probably broken for plugin-defined events.
    - event groups are broken (do we want to keep them?)

src/protocols/unused/HTTP-binpac.h

@@ -0,0 +1,28 @@
+#ifndef http_binpac_h
+#define http_binpac_h
+
+#include "TCP.h"
+
+#include "http_pac.h"
+
+class HTTP_Analyzer_binpac : public TCP_ApplicationAnalyzer {
+public:
+	HTTP_Analyzer_binpac(Connection* conn);
+	virtual ~HTTP_Analyzer_binpac();
+
+	virtual void Done();
+	virtual void DeliverStream(int len, const u_char* data, bool orig);
+	virtual void Undelivered(int seq, int len, bool orig);
+	virtual void EndpointEOF(bool is_orig);
+
+	static analyzer::Analyzer* InstantiateAnalyzer(Connection* conn)
+		{ return new HTTP_Analyzer_binpac(conn); }
+
+	static bool Available()
+		{ return (http_request || http_reply) && FLAGS_use_binpac; }
+
+protected:
+	binpac::HTTP::HTTP_Conn* interp;
+};
+
+#endif