This reverts commit 36135fc5.

Window-related functions is guarded from calls from application code.
Old implementations with "no-gui" exception are stell compiled and linked to OpenCV library for binary compatibility.

this fixes 64-bit MSVC warning

expanded cv::threshold parallelization to other threading frameworks; fixed potential bug with unprocessed bottom of the image; fixed build problem in stitching

Diagram rendering script updated.

OpenCV info library name fixed;
Minimum API level for OpenCV library project increased up to 3 for using message dialogs.