Add PNG versions of our SVG icons

This is just a temporary workaround while we figure out why the Windows
build doesn't load SVGs correctly. To avoid messing with the build system
I simply switch to using PNG everywhere.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

subsurface.qrc

@@ -8,13 +8,18 @@
 	<file alias="advanced">icons/advanced.png</file>
 	<file alias="edit">icons/advanced.png</file>
 	<file alias="graph">icons/graph.png</file>
-	<file alias="minimum">icons/minimum.svg</file>
-	<file alias="maximum">icons/maximum.svg</file>
-	<file alias="average">icons/average.svg</file>
+<!--	<file alias="minimum">icons/minimum.svg</file> -->
+	<file alias="minimum">icons/minimum.png</file>
+<!--	<file alias="maximum">icons/maximum.svg</file> -->
+	<file alias="maximum">icons/maximum.png</file>
+<!--	<file alias="average">icons/average.svg</file> -->
+	<file alias="average">icons/average.png</file>
 	<file alias="warning">icons/warning.png</file>
 	<file alias="table-css">qt-ui/css/tableviews.css</file>
-	<file alias="scale">icons/scale.svg</file>
-	<file alias="ruler">icons/ruler.svg</file>
+<!--	<file alias="scale">icons/scale.svg</file> -->
+	<file alias="scale">icons/scale.png</file>
+<!--	<file alias="ruler">icons/ruler.svg</file> -->
+	<file alias="ruler">icons/ruler.png</file>
 	<file alias="arrow_up">icons/planner/arrow_up.png</file>
 	<file alias="arrow_down">icons/planner/arrow_down.png</file>
 	<file alias="icon_time">icons/planner/icon_time.png</file>