Callback output, split SDK

• Add a callback output for pull-based components without time step
• Add property is_push_based to IOutput to indicate if data must be pushed
• Handle pull-based inputs in ConnectHelper/try_connect
• Log warning when a time component was not updated during a run
• Split module sdk, as it exceeded 1000 lines of code
• Add tests

Fixes #22 (closed)

Pull-based components/outputs offer one more way to build non-working compositions. We should check for them! Continued in #49 (closed).

src/finam/core/sdk/input.py

@@ -180,7 +180,7 @@ class CallbackInput(Input):
     Parameters
     ----------
     callback : callable
-        A callback ``callback(data, time)``, returning the transformed data.
+        A callback ``callback(caller, time)``, returning the transformed data.
     """
 
     def __init__(self, callback, name, info=None, **info_kwargs):