bring back imports to __init__ of core and view (#904)

for backward compatibility

neurom/core/__init__.py

@@ -27,3 +27,8 @@
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 """Core functionality and data types of NeuroM."""
+
+# those imports here for backward compatibility
+from neurom.core.soma import Soma
+from neurom.core.neuron import Section, Neurite, Neuron
+from neurom.core.population import Population

neurom/geom/__init__.py

@@ -31,6 +31,7 @@
 import numpy as np
 from scipy.spatial import ConvexHull
 from neurom.core.dataformat import COLS
+from neurom.geom.transform import translate, rotate
 
 
 def bounding_box(obj):

neurom/view/__init__.py

@@ -27,3 +27,7 @@
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 """View tools to visualize morphologies."""
+from neurom.view.view import (plot_neuron, plot_neuron3d,
+                              plot_tree, plot_tree3d,
+                              plot_soma, plot_soma3d,
+                              plot_dendrogram)