EXT-7045 FIX Group profile not using placeholder art

add placeholder art, add code to convert texture name to ID since LLTextureCtrl can't accept textures by name...
Reviwed V.Savchuk at https://codereview.productengine.com/secondlife/r/378

--HG--
branch : product-engine

indra/newview/llpanelgroupgeneral.cpp

@@ -846,6 +846,17 @@ void LLPanelGroupGeneral::reset()
 	
 	mInsignia->setEnabled(true);
 
+	LLPointer<LLUIImage> imagep = LLUI::getUIImage(mInsignia->getDefaultImageName());
+	if(imagep)
+	{
+		LLViewerFetchedTexture* pTexture = dynamic_cast<LLViewerFetchedTexture*>(imagep->getImage().get());
+		if(pTexture)
+		{
+			LLUUID id = pTexture->getID();
+			mInsignia->setImageAssetID(id);
+		}
+	}
+
 	{
 		std::string empty_str = "";
 		mEditCharter->setText(empty_str);

indra/newview/skins/default/textures/textures.xml

@@ -135,6 +135,7 @@ with the same filename but different name
   <texture name="ForwardArrow_Press" file_name="icons/ForwardArrow_Press.png" preload="false" />
 
   <texture name="Generic_Group" file_name="icons/Generic_Group.png" preload="false" />
+  <texture name="Generic_Group_Large" file_name="icons/Generic_Group_Large.png" preload="false" />
   <texture name="icon_group.tga" file_name="icons/Generic_Group.png" preload="false" />
   <texture name="Generic_Object_Small" file_name="icons/Generic_Object_Small.png" preload="false" />
   <texture name="Generic_Person" file_name="icons/Generic_Person.png" preload="false" />

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

@@ -28,6 +28,7 @@ Hover your mouse over the options for more help.
       width="304"
       layout="topleft">
     <texture_picker
+     default_image_name="Generic_Group_Large"
      follows="left|top"
      height="110"
      label=""