Refactoring: rename tools/editor/ to editor/

The other subfolders of tools/ had already been moved to either
editor/, misc/ or thirdparty/, so the hiding the editor code that
deep was no longer meaningful.

editor/doc/SCsub

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+
+Import('env')
+
+env.add_source_files(env.editor_sources, "*.cpp")
+
+Export('env')