New option to send canvas to render buffer

allows to use 3D environment effects for post processing such as Glow,
Bloom, HDR, etc. in 2D.

demos/2d/hdr/beach_cave.gd

@@ -0,0 +1,26 @@
+
+extends Node2D
+
+# member variables here, example:
+# var a=2
+# var b="textvar"
+const CAVE_LIMIT=1000
+
+func _input(ev):
+	if (ev.type==InputEvent.MOUSE_MOTION and ev.button_mask&1):
+		var rel_x = ev.relative_x
+		var cavepos = get_node("cave").get_pos()
+		cavepos.x+=rel_x
+		if (cavepos.x<-CAVE_LIMIT):
+			cavepos.x=-CAVE_LIMIT
+		elif (cavepos.x>0):
+			cavepos.x=0
+		get_node("cave").set_pos(cavepos)
+			
+
+func _ready():
+	set_process_input(true)
+	# Initialization here
+	pass
+
+

demos/2d/hdr/engine.cfg

@@ -0,0 +1,13 @@
+[application]
+
+name="HDR for 2D"
+main_scene="res://beach_cave.scn"
+
+[display]
+
+width=1080
+height=720
+
+[rasterizer]
+
+blur_buffer_size=128

demos/2d/hdr/ocean_beach.png.flags

@@ -0,0 +1 @@
+tolinear=true

demos/2d/hdr/ocean_cave.png.flags

@@ -0,0 +1 @@
+tolinear=true