Fixed vs2013 compatibility with cmath. Play and Directory Button Changes

\<math.h\> is deprecated in c++ and won't compile in VS2013. Changed to \<cmath\>

Play button now handles directories differently. It looks in the directory for the first file without the word sample in it that has one of the extensions listed in the options by the user. It plays this file or just opens the directory if no file is found.

Directory button now opens the directory the movie is in. It won't handle cases where the movie is nested deeper like CD1/CD2. 

VS2013 made some tiny changes to the project files. I didn't want to create a new file. I'm not sure if its back compatible with VS2010, making the VS2010 directory name outdated.