Show confirm dialog before permanently erasing keyboard config (the confirm dialog I added is reusable, so should we ever need another confirm dialog we can reuse this one)

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@5931 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/gui/confirm_dialog.stkgui

@@ -0,0 +1,19 @@
+<stkgui>
+
+<div x="2%" y="10%" width="96%" height="80%" layout="vertical-row" >
+
+    <label id="title" width="100%" text_align="center" word_wrap="true" proportion="1" />
+
+    <spacer height="25" width="10" />
+
+    <button id="confirm" I18N="In a 'are you sure?' dialog" text="Yes" align="center"/>
+    
+    <spacer height="15" width="10" />
+    
+    <button id="cancel" I18N="In a 'are you sure?' dialog" text="Cancel" align="center"/>
+
+    <spacer height="10" width="10" />
+    
+</div>
+
+</stkgui>