UI: Fix dock titlebar icons not loading

The icons had the wrong name in the qss files. The docks were missing
the icons on at least Linux. I have no idea why the dock icons still
worked on Windows though.

UI/data/themes/Acri.qss

@@ -300,8 +300,8 @@ QDockWidget {
     font-size: 10.5pt;
     font-weight: bold;
 
-    titlebar-close-icon: url('./Dark/Close.svg');
-    titlebar-normal-icon: url('./Dark/Popout.svg');
+    titlebar-close-icon: url('./Dark/close.svg');
+    titlebar-normal-icon: url('./Dark/popout.svg');
 }
 
 QDockWidget::title {

UI/data/themes/Grey.qss

@@ -300,8 +300,8 @@ QDockWidget {
     font-size: 10.5pt;
     font-weight: bold;
 
-    titlebar-close-icon: url('./Dark/Close.svg');
-    titlebar-normal-icon: url('./Dark/Popout.svg');
+    titlebar-close-icon: url('./Dark/close.svg');
+    titlebar-normal-icon: url('./Dark/popout.svg');
 }
 
 QDockWidget::title {

UI/data/themes/Light.qss

@@ -300,8 +300,8 @@ QDockWidget {
     font-size: 10.5pt;
     font-weight: bold;
 
-    titlebar-close-icon: url('./Light/Close.svg');
-    titlebar-normal-icon: url('./Light/Popout.svg');
+    titlebar-close-icon: url('./Light/close.svg');
+    titlebar-normal-icon: url('./Light/popout.svg');
 }
 
 QDockWidget::title {

UI/data/themes/Rachni.qss

@@ -302,8 +302,8 @@ QDockWidget {
     font-size: 10.5pt;
     font-weight: bold;
 
-    titlebar-close-icon: url('./Dark/Close.svg');
-    titlebar-normal-icon: url('./Dark/Popout.svg');
+    titlebar-close-icon: url('./Dark/close.svg');
+    titlebar-normal-icon: url('./Dark/popout.svg');
 }
 
 QDockWidget::title {

UI/data/themes/Yami.qss

@@ -304,8 +304,8 @@ QDockWidget {
     font-size: 10.5pt;
     font-weight: bold;
 
-    titlebar-close-icon: url('./Dark/Close.svg');
-    titlebar-normal-icon: url('./Dark/Popout.svg');
+    titlebar-close-icon: url('./Dark/close.svg');
+    titlebar-normal-icon: url('./Dark/popout.svg');
 }
 
 QDockWidget::title {