Added pause menu to ScreenGameplay in default theme. Added SetPrevScreenName lua binding to Screen. Added begin_backing_out lua binding to ScreenGameplay.

Docs/Luadoc/Lua.xml

@@ -1455,6 +1455,7 @@
 			<Function name='PostScreenMessage'/>
 			<Function name='RemoveInputCallback'/>
 			<Function name='SetNextScreenName'/>
+			<Function name='SetPrevScreenName'/>
 			<Function name='String'/>
 			<Function name='lockinput'/>
 		</Class>
@@ -1466,6 +1467,7 @@
 			<Function name='GetStageStats'/>
 		</Class>
 		<Class base='ScreenWithMenuElements' name='ScreenGameplay'>
+			<Function name='begin_backing_out'/>
 			<Function name='Center1Player'/>
 			<Function name='GetDummyPlayerInfo'/>
 			<Function name='GetHasteRate'/>

Docs/Luadoc/LuaDocumentation.xml

@@ -4307,6 +4307,9 @@ save yourself some time, copy this for undocumented things:
 	<Function name='SetNextScreenName' return='void' arguments='string name'>
 		Sets the NextScreen value to name.
 	</Function>
+	<Function name='SetPrevScreenName' return='void' arguments='string name'>
+		Sets the PrevScreen value to name.
+	</Function>
 	<Function name='String' theme='_fallback' return='string' arguments='string sName'>
 		[02 Other.lua] Gets a string from the current Screen in the current language.
 	</Function>
@@ -4322,6 +4325,9 @@ save yourself some time, copy this for undocumented things:
 	</Function>
 </Class>
 <Class name='ScreenGameplay'>
+	<Function name='begin_backing_out' return='' arguments=''>
+		This should behave identically to the normal back button behavior.  This function is for the pause menu to use when the player forfeits or restarts, so that a score isn't saved.
+	</Function>
 	<Function name='Center1Player' return='bool' arguments=''>
 		Returns <code>true</code> if a single <Link class='Player' /> has its NoteField centered.
 	</Function>