Introduce XML documentation for:

  - MeetMe()
  - MeetMeCount()
  - MeetMeChannelAdmin()
  - MeetMeAdmin()
  - SLAStation()
  - SLATrunk()

- Add an attribute to optionlist 'hasparams' with the same functionality as the one
we have in <parameter> and <argument> (the DTD was updated)
- Fix a leak when getting an attribute while parsing an <optionlist>.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@156575 65c4cc65-6c06-0410-ace0-fbb531ad65f3