Streamline (settings) hotkey handling

This moves all hotkeys that were accessible in the audio/publish
settings panes to a new hotkeys settings pane

Also makes the push to talk hotkeys behave like all other (settings)
hotkeys, i.e. as long as a hotkey is configured the hotkey is active
Extract out file naming and file stream creation from OBS::StartRecording
Track pts of encoded pictures
Pass pts of encoded picture to file streams
Add ReplayBuffer

Buffers at least the configured amount of seconds of video and audio
packets and writes them to a new file when SaveReplayBuffer is called
Add Save Interval support to UI/recording logic
Fix stop signal types in QSV encoder
Make QSV stop signal reset manual
Implement QSV encoder flushing
Update Intel MediaSDK to 2014 R2

Contains a minor edit to the downloaded files, see
https://software.intel.com/en-us/forums/topic/519877
Add new QSV API versions
Refactor setting pane initialization
Add support for encoder settings panes
Exit QSVHelper when encoder init fails
Handle QSVHelper hangs more gracefully
Fix QSV parameters copy constructor
Refactor QSV parameters ext buffers initialization
Add QSV parameter ext coding options
Add QSV parameters dump function
Add custom parameters for QSV rate control modes

Custom parameters can be set via profile settings. This also allows
selecting newer modes such as look ahead modes on Haswell+.