Apply general GPU acceleration enable for encoders capable to use it.

@SubJunk and @SharkHunter I try to finished applying general GPU acceleration setting for encoders capable to use it. Please check it or recommend different approach. Maybe the GPU acceleration setting in each encoders setting tabs could be removed and  used only general setting or it could be leaved as it is and and the general setting is not ussefull and it can be removed. What is your opinion?