VSF TR-10-1 compatibility

[N-Nagorny]

sdpoker indicates a=mediaclk:sender as an error.

The 'direct' reference for the mediaclk parameter should be used, as per ST 2110-10 Section 8.1. Found 'a=mediaclk:sender'.

ST 2110-10:2017 Section 8.1 says

All stream descriptions shall have a media-level mediaclk attribute as per IETF RFC 7273 section 5.2. The
direct reference should be used.

ST 2110-10:2017 Section 2 says

The keywords, "should" and "should not" indicate that, among several possibilities, one is recommended as
particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but
not necessarily required; or that (in the negative form) a certain possibility or course of action is deprecated
but not prohibited.

VSF TR-10-1 overrides ST 2110-10:2017 Section 8.1 saying

If the Media Clock is asynchronous with respect to the Internal Clock, for example if Async
Media is present at the input of a Sender, the following form shall be used:
a=mediaclk:sender

Is there a room in sdpoker to handle this case?