Add class definition and initial docstring

src/ari_sxn_common/common_bluesky.py

@@ -0,0 +1,21 @@
+from bluesky import plans
+from bluesky.plan_stubs import mv, mvr
+
+class PlanCollector:
+    """
+    A class used to collect together the plans to be used at ARI and SXN,
+
+    This is a 'collector' class that is designed to hold together the plans that
+    are used at both ARI and SXN. It will include all of the builtin
+    `bluesky.plans` (but only one alias of each) as well as the builtin
+    `bluesky.plan_stubs` mv (as `plan.move`) and mvr (as `plan.relative_move`).
+    Additional, ARI & SXN specific, plans can/will also be added (see attribute
+    list below).
+
+    Attributes
+    ----------
+    built-ins : many
+        All of the built-in plans from `bluesky.plans` (but not aliases) as well
+        as the `bluesky.plan_stubs` mv (as move) and mvr (as relative_move).
+
+    """