* core:add OPENCV_IPP_MEAN/MINMAX/SUM option to enable IPP optimizations
* fix: to use guard HAVE_IPP and ocv_append_source_file_compile_definitions() macro.
* support OPENCV_IPP_ENABLE_ALL
* add document for OPENCV_IPP_ENABLE_ALL
* fix OPENCV_IPP_ENABLE_ALL comment
* Replaced most remaining sprintf with snprintf
* Deprecated encodeFormat and introduced new method that takes the buffer length
* Also increased buffer size at call sites to be a little bigger, in case int is 64 bit