use icons for PlayerListDialog buttons

res/app.qrc

@@ -9,12 +9,13 @@
         <file>5sync-96.png</file>
         <file>5sync-128.png</file>
         <file>5sync-256.png</file>
+        <file>add.svgz</file>
         <file>avatararea.png</file>
         <file>avatarareaimport.png</file>
-        <file>back.svg</file>
+        <file>back.svgz</file>
         <file>empty1x16.png</file>
         <file>mappreview.jpg</file>
-        <file>next.svg</file>
+        <file>next.svgz</file>
         <file>pointmaker-8.png</file>
         <file>pointmaker-16.png</file>
         <file>pointmaker-24.png</file>

res/back.svg

@@ -1 +0,0 @@
-<?xml version="1.0" ?><!DOCTYPE svg  PUBLIC '-//W3C//DTD SVG 1.1//EN'  'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'><svg height="512px" id="Layer_1" style="enable-background:new 0 0 512 512;" version="1.1" viewBox="0 0 512 512" width="512px" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><polygon points="352,115.4 331.3,96 160,256 331.3,416 352,396.7 201.5,256 "/></svg>

res/next.svg

@@ -1 +0,0 @@
-<?xml version="1.0" ?><!DOCTYPE svg  PUBLIC '-//W3C//DTD SVG 1.1//EN'  'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'><svg height="512px" id="Layer_1" style="enable-background:new 0 0 512 512;" version="1.1" viewBox="0 0 512 512" width="512px" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><polygon points="160,115.4 180.7,96 352,256 180.7,416 160,396.7 310.5,256 "/></svg>