Reference update

[aboba]

A number of the drafts referenced now have updated versions, so that the reference section should be updated.

In addition, new terminology relating to transport modes has been introduced in the Grouping Taxonomy document, and probably should be referenced informatively.

In Section 1.1, change:

"The term SST-SS refers to an SVC implementation that transmits all layers within a single RTP session, using a single SSRC. The term SST-MS refers to an SVC implementation that transmits all layers within a single RTP session, using a distinct SSRC for each layer."

To:

"The term SRST, defined in [GROUPING] Section 3.7, refers to an SVC implementation that transmits all layers within a single RTP session, using a single SSRC. The term MRST, defined in [GROUPING] Section 3.7, refers to an SVC implementation that transmits all layers within a single RTP session, using a distinct SSRC for each layer."

Add the following informative reference:

[GROUPING]
J. Lennox; K. Gross; S. Nandakumar; G. Salgueiro; B. Burman. RTP Grouping Taxonomy. 05 March 2015. Internet Draft (work in progress). URL: https://tools.ietf.org/html/draft-ietf-avtext-rtp-grouping-taxonomy