Minor Python scripting fixes.

* Actually install the contents of the pcbnew/scripting/plugins directory on
  Windows and Linux
* Move the test for existence of a directory before adding it to the Python
  system library paths when loading the Python plugins.

pcbnew/CMakeLists.txt

@@ -670,12 +670,13 @@ if( KICAD_SCRIPTING )
             COMMENT "Copying pcbnew.py into ${PYTHON_DEST}"
             )
         add_dependencies( ScriptingPcbnewPyCopy ScriptingWxpythonCopy )
-        # scripting plugins
-        install( DIRECTORY ${PROJECT_SOURCE_DIR}/pcbnew/scripting/plugins/
-            DESTINATION ${KICAD_DATA}/scripting/plugins
-            COMPONENT binary
-            )
     endif()
+
+    # scripting plugins
+    install( DIRECTORY ${PROJECT_SOURCE_DIR}/pcbnew/scripting/plugins/
+        DESTINATION ${KICAD_DATA}/scripting/plugins
+        FILE_PERMISSIONS OWNER_EXECUTE OWNER_READ OWNER_WRITE GROUP_EXECUTE GROUP_READ WORLD_EXECUTE WORLD_READ
+    )
 endif()
 
 if( KICAD_SCRIPTING_MODULES )

scripting/kicadplugins.i

@@ -101,11 +101,11 @@ def LoadPlugins( plugpath ):
                 plugin_directories.append( os.path.join( singlepath, 'scripting', 'plugins') )
 
     for plugins_dir in plugin_directories:
-        sys.path.append(plugins_dir)
-
         if not os.path.isdir(plugins_dir):
             continue
 
+        sys.path.append(plugins_dir)
+
         for module in os.listdir(plugins_dir):
             if os.path.isdir(plugins_dir+module):
                 __import__(module, locals(), globals())