Finish implementation of copy method.

All types (besides EntropyVal) now support a native copy operation,
which uses primitives of the underlying datatypes to perform a quick
copy, without serialization.

EntropyVal is the one exception - since that type is rather complex
(many members) and will probably not be copied a lot, if at all, it
makes sense to just use the serialization function.

This will have to be slightly re-written in the near-term-future to use
the new serialization function for that opaque type.

This change also introduces a new x509_from_der bif, which allows to
parse a der into an opaque of x509.

This change removes the d2i_X509_ wrapper function; this was a remnant
when d2i_X509 took non-const arguments. We directly use d2i_X509 at
several places assuming const-ness, so there does not seem to ba a
reason to keep the wrapper.

This change also exposed a problem in the File cache - cases in which an
object was brought back into the cache, and writing occurred in the
file_open event were never correctly handeled as far as I can tell.

src/file_analysis/analyzer/x509/X509.h

@@ -123,6 +123,15 @@ public:
 	 */
 	explicit X509Val(::X509* certificate);
 
+	/**
+	 * Clone an X509Val
+	 *
+	 * @param state certifies the state of the clone operation (duplicate tracking)
+	 *
+	 * @return A cloned X509Val.
+	 */
+	Val* DoClone(CloneState* state) override;
+
 	/**
 	 * Destructor.
 	 */