fixing the exported presentation when there's no video in the session
Merge branch 'presentation-export' into mconf-live0.4.3
Merge branch 'v0.81' into record-button

Conflicts:
	bigbluebutton-client/branding/default/style/css/BBBDefault.css
	bigbluebutton-client/src/org/bigbluebutton/main/views/MainToolbar.mxml
fixing the handling of multiple drawings from a single shape
bug could be easily reproduced typing text, erase part of it and then type again
Merge branch 'record-button' into mconf-live0.4.3

Conflicts:
	bigbluebutton-client/branding/default/style/css/BBBDefault.css