Update axes_type.cpp

Actually now that I come to think of it, this automatic "axes_type::clear()" feature will cause pain for users. It is better to introduce the users with the command and let them clear plots manually instead of forcing it on every object emplacement.

Author: edvinsmineikis

source/matplot/core/axes_type.cpp

@@ -47,7 +47,6 @@ namespace matplot {
         if (next_plot_replace_) {
             children_.clear();
             colororder_index_ = 0;
-            axes_type::clear();
         }
         children_.push_back(obj);
         touch();