Screws.scad is now included in core.scad, so doesn't need to be included

anywhere else. utils/core/core.scad is the old version without fasteners to
be used internally in the library.

utils/core/core.scad

@@ -0,0 +1,39 @@
+//
+// NopSCADlib Copyright Chris Palmer 2018
+// nop.head@gmail.com
+// hydraraptor.blogspot.com
+//
+// This file is part of NopSCADlib.
+//
+// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
+// GNU General Public License as published by the Free Software Foundation, either version 3 of
+// the License, or (at your option) any later version.
+//
+// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with NopSCADlib.
+// If not, see <https://www.gnu.org/licenses/>.
+//
+
+//
+// Include this file to use the miniumum library
+//
+include <../../global_defs.scad>
+//
+// Global functions and modules
+//
+use <global.scad>
+
+module use_stl(name) {               //! Import an STL to make a build platter
+    stl(name);
+
+    import(str("../stls/", name, ".stl"));
+}
+
+module use_dxf(name) {               //! Import a DXF to make a build panel
+    dxf(name);
+
+    import(str("../dxfs/", name, ".dxf"));
+}