Another experiment: made the selection in the nearby media floater track the media impl the media controls are currently referencing (either focus or hover).

EXT-2011 titles of IM sessions aren't aligned to center
EXT-3025 Pick's description overlaps picks name
also moved tool tip param default to tool_tip.xml
also made default param<const LLFontGL*> be SansSerif

reviewed by Leyla

Reviewed (conceptually) by Richard and James

Partial implementation of LLFloaterNearbyMedia::refreshList(), with many TODO sections and a bit of ifdef-ed out pseudocode.

Initial pass at LLViewerMediaImpl::getProximity().  Currently it just returns the position in the priority list, but that will change.

Floater drag handle visibility/enablement was getting lost during construction.
Reviewed with Richard.

https://jira.secondlife.com/browse/EXT-2006

Old behavior was setting your skin to white, since they were defaulting to the blank texture.
-Reviewed by nyx

UI widget that references "slt" in the XML.

Added LLViewerMediaImpl::set/getDisabled(), which will prevent a media instance from loading.

Added LLViewerMedia::set/getInWorldMediaDisabled(), which will disable all inworld media fom loading.

Added LLViewerMedia::getPriorityList() and made the priority comparitor public.

Mutes media on preview widget in media settings/general panel

EXT-1936 - [BSI] Reversion - clicking on avatar name in group chat should bring up profile
also fixed buttons not working on avatar list in IM window

reviewed by Leyla

LLNavigationBar was passing coordinates to LLMenuGL::showPopup() in the wrong
coordinate frame.  Added comments to LLMenuGL to clarify which coordinate
frame to use.  Not reviewed.

LLMediaPluginTest test app. We do not copy over the
example plugin to the Second Life client plugin dir.