Guideline 1.5 - Provide volume configuration

Guideline 1.5 seems to have become corrupted when we cut the guideline "Provide volume configuration" down from two SC, one about global volume and one about individual tracks, down to one, just about individual tracks.

The sole SC now reads "1.5.1 Global Volume: The user can independently adjust the volume of all audio tracks, relative to the global volume level set through operating environment mechanisms. (Level A)".

The SC itself is clearly about adjusting individual audio tracks *relative to* the global volume setting. However, that conflicts with both the title and the Intent paragraph, both of which are about adjusting the global volume rather than individual tracks.

The title and Intent are left over from older drafts where there were two SC reading:

* 3.7.1 Global Volume: The user can globally set volume of all audio tracks it renders (including a "mute" setting) through available operating environment mechanisms. (Level A)

* 3.7.2 Speech Volume: The user agent allows the user to adjust the volume of all audio tracks it renders, independent or relative to the volume level at the operating environment.

     Thanks,
     Greg