Add the @2x expert indicators.

We currently load the expert indicator resources using an <img> tag.
According to QTBUG-36383 the @2x versions won't load unless you've built
with Qt 5.4.0 or later.

Change-Id: I003fd5d5f10e779f2e7ca6ba9fbb8e033df85b80
Reviewed-on: https://code.wireshark.org/review/7601
Reviewed-by: Gerald Combs <gerald@wireshark.org>

Makefile.am

@@ -898,11 +898,16 @@ EXTRA_DIST = \
 	image/dumpcap.rc.in	\
 	image/editcap.rc.in	\
 	image/expert_chat.png	\
+	image/expert_chat@2x.png	\
 	image/expert_error.png	\
+	image/expert_error@2x.png	\
 	image/expert_indicators.svg	\
 	image/expert_none.png	\
+	image/expert_none@2x.png	\
 	image/expert_note.png	\
+	image/expert_note@2x.png	\
 	image/expert_warn.png	\
+	image/expert_warn@2x.png	\
 	image/file_dlg_win32.rc \
 	image/hi16-app-wireshark.png	\
 	image/hi32-app-wireshark.png	\

image/status.qrc

@@ -1,10 +1,15 @@
 <RCC>
     <qresource prefix="/expert">
         <file>expert_chat.png</file>
+        <file>expert_chat@2x.png</file>
         <file>expert_error.png</file>
+        <file>expert_error@2x.png</file>
         <file>expert_none.png</file>
+        <file>expert_none@2x.png</file>
         <file>expert_note.png</file>
+        <file>expert_note@2x.png</file>
         <file>expert_warn.png</file>
+        <file>expert_warn@2x.png</file>
     </qresource>
     <qresource prefix="/comment">
         <file>capture_comment_update.png</file>

ui/qt/main_status_bar.cpp

@@ -190,6 +190,8 @@ void MainStatusBar::hideExpert() {
 }
 
 void MainStatusBar::expertUpdate() {
+    // <img> won't load @2x versions in Qt versions earlier than 5.4.
+    // We might have to switch to a QPushButton.
     QString img_text = "<img src=\":/expert/expert_";
     QString tt_text = tr(" is the highest expert info level");