Fix various documentation, mostly related to file analysis.

- Fix examples/references in the file analysis how-to/usage doc.

- Add Broxygen-generated docs for file analyzer plugins.

- Break FTP::Info type declaration out in to its own file to get
  rid of some circular dependencies (between s/b/p/ftp/main and
  s/b/p/ftp/utils).

src/file_analysis/Manager.cc

@@ -394,3 +394,8 @@ const char* Manager::GetAnalyzerName(int tag) const
 
 	return it->second->CanonicalName();
 	}
+
+EnumType* Manager::GetTagEnumType()
+	{
+	return tag_enum_type;
+	}