Edl handling change

Updated the CDVDPlayer class so that it supports scene seeking. Edl class supported scene markers however functionality was omitted from DVDPlayer and could not be previously used. Scene seeking is now triggered in the same manner as chapter seeking.

Minor updates were also made to the CEdl class. A new method was created which, as its name describes, adds scene markers for COMM_BREAKs. New method is called at the end of ReadEditDecisionLists and will only add scene markers if the EDL file does not specify any scene markers. I also made a temporary workaround for bug #15207 where EDL cuts cause video seeking to act erratically. The temporary workaround was to treat the CUTs as COMM_BREAKs which work perfectly fine.

I have tested this functionality on both Windows and on RPi with a development build of openelec. This is my first pull request and my first foray into open source development so please excuse any stark omissions. I tried to abide by all of your contribution guidelines but may have missed one here or there.