python: bindings loader package

Configures and loads OpenCV bindings extension including 3rdparty dependencies

Based on running Python specify:
- configure PYTHON_PATH (via "sys.path")
- configure LD_LIBRARY_PATH / PATH

modules/python/CMakeLists.txt

@@ -3,11 +3,10 @@
 # ----------------------------------------------------------------------------
 if(DEFINED OPENCV_INITIAL_PASS)  # OpenCV build
 
-add_subdirectory(bindings)
-
 if(ANDROID OR APPLE_FRAMEWORK OR WINRT)
-  set(__disable_python2 ON)
-  set(__disable_python3 ON)
+  ocv_module_disable_(python2)
+  ocv_module_disable_(python3)
+  return()
 elseif(BUILD_opencv_world OR (WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug"))
   if(NOT DEFINED BUILD_opencv_python2)
     set(__disable_python2 ON)
@@ -17,6 +16,12 @@ elseif(BUILD_opencv_world OR (WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug"))
   endif()
 endif()
 
+add_subdirectory(bindings)
+
+if(NOT OPENCV_SKIP_PYTHON_LOADER)
+  include("./python_loader.cmake")
+endif()
+
 if(__disable_python2)
   ocv_module_disable_(python2)
 endif()