Changes from 26/8/2014 (skipped 23/8/2014).

Changelog:
2014.08.26:
- Fixed a bug that was introduced in version 2014.03.25 that could cause excessive CPU usage
  for servers that stream from a single source to both RTP/UDP and RTP/TCP clients.
  Thanks to Chris Richardson for noting this.

2014.08.23:
- Added a new function "attrVal_strToLower()" to "MediaSubsession".  This returns a string
  attribute as a lower-case string.  ("mode" SDP attributes are now looked up using this function.)
  (Thanks to James Huang for noting a problem that made this necessary.)
- Added an alternative form of "strDupSize()" (in the "UsageEnvironment" library) that
  also returns the size of the allocated buffer.