Command: Code cleanup, added ::category accessor

- The Command object failed to initialize all member on construction and
  initialized them out of order (is this still a thing in C++11?).
- The _category was the only member with no accessor, which is not right.

src/commands/Command.cpp

@@ -213,7 +213,7 @@ const std::map <Command::Category, std::string> Command::categoryNames =
 
 ////////////////////////////////////////////////////////////////////////////////
 Command::Command ()
-: _category(Category::unassigned)
+: _keyword ("")
 , _usage ("")
 , _description ("")
 , _read_only (true)
@@ -221,8 +221,10 @@ Command::Command ()
 , _needs_confirm (false)
 , _needs_gc (true)
 , _uses_context (false)
-, _accepts_filter (true)
-, _accepts_modifications (true)
+, _accepts_filter (false)
+, _accepts_modifications (false)
+, _accepts_miscellaneous (false)
+, _category(Category::unassigned)
 , _permission_quit (false)
 , _permission_all (false)
 , _first_iteration (true)
@@ -294,6 +296,12 @@ bool Command::accepts_miscellaneous () const
   return _accepts_miscellaneous;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+Command::Category Command::category () const
+{
+  return _category;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Returns true or false indicating whether to proceed with a write command, on
 // a per-task basis, after (potentially) asking for permission.