Bump version to 3.1.2-rc

modules/mono/doc_classes/@C#.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="@C#" category="Core" version="3.1.1">
+<class name="@C#" category="Core" version="3.1.2">
 	<brief_description>
 	</brief_description>
 	<description>

modules/mono/doc_classes/CSharpScript.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="CSharpScript" inherits="Script" category="Core" version="3.1.1">
+<class name="CSharpScript" inherits="Script" category="Core" version="3.1.2">
 	<brief_description>
 	</brief_description>
 	<description>

modules/mono/doc_classes/GodotSharp.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="GodotSharp" inherits="Object" category="Core" version="3.1.1">
+<class name="GodotSharp" inherits="Object" category="Core" version="3.1.2">
 	<brief_description>
 	</brief_description>
 	<description>

version.py

@@ -3,7 +3,7 @@ name = "Godot Engine"
 major = 3
 minor = 1
 patch = 2
-status = "devel"
+status = "rc"
 module_config = ""
 year = 2019
 website = "https://godotengine.org"