feat(pm4py): removed strong dependencies on intervaltree and stringdist

removed strong dependencies on intervaltree and stringdist

pm4py/algo/conformance/alignments/__init__.py

@@ -1 +1,5 @@
-from pm4py.algo.conformance.alignments import decomposed, dfg, edit_distance, petri_net, process_tree
+from pm4py.algo.conformance.alignments import decomposed, dfg, petri_net, process_tree
+import pkgutil
+
+if pkgutil.find_loader("stringdist"):
+    from pm4py.algo.conformance.alignments import edit_distance

pm4py/algo/transformation/__init__.py

@@ -1 +1,4 @@
-from pm4py.algo.transformation import log_to_trie, log_to_features, log_to_interval_tree
+from pm4py.algo.transformation import log_to_trie, log_to_features
+import pkgutil
+if pkgutil.find_loader("intervaltree"):
+    from pm4py.algo.transformation import log_to_interval_tree

pm4py/statistics/__init__.py

@@ -1,3 +1,5 @@
 from pm4py.statistics import traces, attributes, variants, start_activities, end_activities, util, \
-    sojourn_time, concurrent_activities, eventually_follows, overlap, rework
-
+    sojourn_time, concurrent_activities, eventually_follows, rework
+import pkgutil
+if pkgutil.find_loader("intervaltree"):
+    from pm4py.statistics import overlap