introduce the pytest_configure_funcargs hook for better control on funcarg instanciation/configuration

doc/funcargs.txt

@@ -115,6 +115,9 @@ think of as "resources").
 .. _`funcarg factory`:
 .. _factory:
 
+
+
+
 The funcarg **request** object
 =============================================
 
@@ -140,6 +143,16 @@ factory and provides access to test configuration and context:
 .. _`parametrizing-tests`:
 .. _`parametrized test functions`:
 
+
+Reconfiguring funcargs in a test's setup
+========================================
+
+Sometimes there is need to do additional funcarg setup steps
+which are outside of the normal setup and involve more than just one funcarg.
+For that reason the ``pytest_configure_funcargs(request)`` hook
+is called to implement and extend the funcarg filling mechanism.
+
+
 Parametrizing multiple calls to a test function
 ===========================================================