Feature: Extra arg detection

- Commands that do not accept filters or modifications now generate an error
  when extra arguments are specified.

src/commands/CmdSync.cpp

@@ -29,6 +29,7 @@
 #include <inttypes.h>
 #include <signal.h>
 #include <Context.h>
+#include <Filter.h>
 #include <Color.h>
 #include <text.h>
 #include <util.h>
@@ -54,6 +55,10 @@ int CmdSync::execute (std::string& output)
 #ifdef HAVE_LIBGNUTLS
   std::stringstream out;
 
+  Filter filter;
+  if (filter.hasFilter ())
+    throw std::string (STRING_ERROR_NO_FILTER);
+
   // Loog for the 'init' keyword to indicate one-time pending.data upload.
   bool first_time_init = false;
   std::vector <std::string> words = context.cli2.getWords ();