Improve outdated README files and improve simple C++ demo

cpp/simple/project/default_env.tres

@@ -1,18 +0,0 @@
-[gd_resource type="Environment" load_steps=2 format=2]
-
-[sub_resource type="ProceduralSky" id=1]
-radiance_size = 4
-sky_top_color = Color( 0.0470588, 0.454902, 0.976471, 1 )
-sky_horizon_color = Color( 0.556863, 0.823529, 0.909804, 1 )
-sky_curve = 0.25
-ground_bottom_color = Color( 0.101961, 0.145098, 0.188235, 1 )
-ground_horizon_color = Color( 0.482353, 0.788235, 0.952941, 1 )
-ground_curve = 0.01
-sun_energy = 16.0
-
-[resource]
-background_mode = 2
-background_sky = SubResource( 1 )
-fog_height_min = 0.0
-fog_height_max = 100.0
-ssao_quality = 0

cpp/simple/project/main.tscn

@@ -24,7 +24,7 @@ __meta__ = {
 "_edit_use_anchors_": false
 }
 
-[node name="Sprite" type="Sprite" parent="."]
+[node name="SimpleSprite" type="Sprite" parent="."]
 position = Vector2( 100, 100 )
 texture = ExtResource( 2 )
 script = ExtResource( 3 )

cpp/simple/project/project.godot

@@ -14,11 +14,14 @@ _global_script_class_icons={
 
 [application]
 
-config/name="New Game Project"
+config/name="Simple GDNative C++ demo"
 run/main_scene="res://main.tscn"
 config/icon="res://icon.png"
 
 [rendering]
 
-quality/driver/fallback_to_gles2=true
-environment/default_environment="res://default_env.tres"
+quality/driver/driver_name="GLES2"
+quality/intended_usage/framebuffer_allocation=0
+quality/intended_usage/framebuffer_allocation.mobile=0
+vram_compression/import_etc=true
+vram_compression/import_etc2=false