Move dxtbx extensions from dxtbx.* to dxtbx.ext.*

Keep them available from the old location, w/ added DeprecationWarnings

Fixes #29

__init__.py

@@ -1,18 +1,33 @@
 from __future__ import absolute_import, division, print_function
 
 import logging
+import warnings
 
-try:
-    import boost.python
-except Exception:
-    ext = None
-else:
-    ext = boost.python.import_ext("dxtbx_ext", optional=True)
+logging.getLogger("dxtbx").addHandler(logging.NullHandler())
 
-if ext is not None:
-    from dxtbx_ext import *
 
-logging.getLogger("dxtbx").addHandler(logging.NullHandler())
+def _deprecate_function(name, func):
+    def _wrapper(*args, **kwargs):
+        warnings.warn(
+            "Addressing dxtbx extensions as dxtbx.{0} is deprecated. Instead use dxtbx.ext.{0}".format(
+                name
+            ),
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return func(*args, **kwargs)
+
+    return _wrapper
+
+
+try:
+    import dxtbx.ext as _ext
+
+    for funcname in dir(_ext):
+        if funcname != "ext" and not funcname.startswith("_"):
+            globals()[funcname] = _deprecate_function(funcname, getattr(_ext, funcname))
+except ImportError:
+    _ext = None
 
 
 class IncorrectFormatError(RuntimeError):

ext.py

@@ -0,0 +1,6 @@
+from __future__ import absolute_import, division, print_function
+
+import boost.python
+
+ext = boost.python.import_ext("dxtbx_ext")
+from dxtbx_ext import *  # noqa: F401,F403