Change close behavior to not end session.

* NOTE: This is functional, but not ideal - it's still closing the floater; we really want to change the behavior of the X button instead.
Also made the group IM floater a little less broken.

indra/newview/llimfloater.cpp

@@ -106,8 +106,6 @@ void LLIMFloater::onFocusReceived()
 // virtual
 void LLIMFloater::onClose(bool app_quitting)
 {
-	if (!gIMMgr->hasSession(mSessionID)) return;
-	
 	setTyping(false);
 	gIMMgr->leaveSession(mSessionID);
 }

indra/newview/skins/default/xui/en/floater_im_session.xml

@@ -10,9 +10,9 @@
  top="0"
  can_close="true"
  can_dock="true"
- can_minimize="true"
+ can_minimize="false"
  visible="true"
- width="350"
+ width="300"
  can_resize="true"
  min_width="300"
  min_height="350">

indra/newview/skins/default/xui/en/panel_group_control_panel.xml

@@ -8,7 +8,7 @@
     <avatar_list
      color="DkGray2"
      follows="left|top|right|bottom"
-     height="130"
+     height="100"
      ignore_online_status="true"
      layout="topleft"
      left="3"
@@ -32,7 +32,6 @@
      background_visible="true"
      bg_alpha_color="0.2 0.2 0.2 1"
      border="false"
-     bottom="1"
      follows="left|bottom"
      height="70"
      left="0"