Fix some issues found by cppcheck

include/chaiscript/dispatchkit/any.hpp

@@ -46,7 +46,7 @@ namespace chaiscript {
       private:
         struct Data
         {
-          Data(const std::type_info &t_type) 
+          explicit Data(const std::type_info &t_type) 
             : m_type(t_type)
           {
           }

include/chaiscript/dispatchkit/bad_boxed_cast.hpp

@@ -40,7 +40,7 @@ namespace chaiscript
         {
         }
 
-        bad_boxed_cast(std::string t_what) CHAISCRIPT_NOEXCEPT
+        explicit bad_boxed_cast(std::string t_what) CHAISCRIPT_NOEXCEPT
           : to(nullptr), m_what(std::move(t_what))
         {
         }