Redefine CPU_xx constants in cv::namespace

This makes them visible from the python bindings
Fix mouse handling in python demos
GSoC Python Tutorials
GSoC Python Tutorials

removed white spaces

removed blank lines at EOF

removed duplicate labels
Merge pull request #1488 from abidrahmank:py_tutorials
Merge pull request #1477 from nzjrs:python-gethardwaresupport
Merge pull request #1429 from nzjrs:fix-sketcher