Move all the basic openscad objects into a new file

This almost halves the size of the main file.
Note that a circular import is necessary, since the base class references the
subclasses

Author: eric-wieser

solid/__init__.py

@@ -1,7 +1,5 @@
 # Some __init__ magic so we can include all solidpython code with:
 #   from solid import *
 #   from solid.utils import *
-try:
-    from solidpython import *
-except ImportError:
-    from solid.solidpython import *
+from .solidpython import *
+from .objects import *