HYPNO: Slow frame rate, navigation issue and frequent sound pops

[antoniou79]

This from testing today with Steam version, on Windows 10, and ScummVM 2.7.0git from HEAD master, built with enable-release.

My observations in comparison to the game running on DosBox (which the Steam version uses):

1. There are frequent "pops" in the audio, very noticeable during gameplay. Non-gameplay videos seem to not have this issue.
2. The framerate in the gameplay feels significantly slower than when playing in DosBox, which feels faster and smoother.
3. When playing in DosBox, moving the mouse towards the edges of the screen causes a bit of a navigation movement (like the view moves up or down or left or right). In the ScummVM version this does not seem to work.