getting this branch up to speed with the unit tests branch

Author: pavelkomarov

.editorconfig

@@ -0,0 +1,6 @@
+root = true
+
+[*.py]
+indent_style = tab
+indent_size = 4
+trim_trailing_whitespace = true

pynumdiff/finite_difference/_finite_difference.py

@@ -17,7 +17,7 @@ def first_order(x, dt, params=None, options={}, num_iterations=None):
              - **dxdt_hat** -- estimated derivative of x
     """
     if params != None and 'iterate' in options:
-        raise DeprecationWarning("""`params` and `options` parameters will be removed in a future version. Use `num_iterations` instead.""")
+        warn("""`params` and `options` parameters will be removed in a future version. Use `num_iterations` instead.""", DeprecationWarning)
         if isinstance(params, list): params = params[0]
         return _iterate_first_order(x, dt, params)
     elif num_iterations: