Mat tutorial - grammar and spelling fixes
Fix CMake variables substitution in Android project files
Revert ffmpeg related changes from "thread-safe VideoWriter and VideoCapture"

This reverts commit 4abf0b31936c96887c028d799c6e89edfc4e197b.

Changes are reverted because they break build of proxy dlls on Windows
Adjust OpenCV version to 2.4.4
Merge pull request #457 from taka-no-me:fix_vars_expansion
Temporary disabled parallel_writers_and_readers test
Merge pull request #416 from asmaloney:mat-docs-cleanup
Merge remote-tracking branch 'upstream/2.4' into TestHighGUI