sceneconverter: make test files resemble a triangle fan.

Need that in order to test certain cases better without having to craft
completely new files.

src/Magnum/SceneTools/Test/SceneConverterTestFiles/quad-duplicates-fuzzy.obj

@@ -1,10 +1,10 @@
-# 1  4--6
+# 3 4--6
 # |\ \ |
 # | \ \|
-# 2--3 5
-v -1  1 0
+# 1--2 5
 v -1 -1 0
 v  1 -1 0
+v -1  1 0
 f 1 2 3
 v -0.9  0.9 0
 v  0.9 -0.9 0

src/Magnum/SceneTools/Test/SceneConverterTestFiles/quad-duplicates.obj

@@ -1,10 +1,10 @@
-# 1 4--6
+# 3 4--6
 # |\ \ |
 # | \ \|
-# 2--3 5
-v -1  1 0
+# 1--2 5
 v -1 -1 0
 v  1 -1 0
+v -1  1 0
 f 1 2 3
 v -1  1 0
 v  1 -1 0

src/Magnum/SceneTools/Test/SceneConverterTestFiles/quad-normals-texcoords.obj

@@ -1,12 +1,12 @@
-# 1 1--4
+# 3 3--4
 # |\ \ |
 # | \ \|
-# 2--3 3
-v -1  1 0
+# 1--2 2
 v -1 -1 0
 v  1 -1 0
+v -1  1 0
 v  1  1 0
 vn 0 0 1
 vt 0 0
 f 1/1/1 2/1/1 3/1/1
-f 1/1/1 3/1/1 4/1/1
+f 3/1/1 2/1/1 4/1/1

src/Magnum/SceneTools/Test/SceneConverterTestFiles/quad.obj

@@ -1,10 +1,10 @@
-# 1 1--4
+# 3 3--4
 # |\ \ |
 # | \ \|
-# 2--3 3
-v -1  1 0
+# 1--2 2
 v -1 -1 0
 v  1 -1 0
+v -1  1 0
 v  1  1 0
 f 1 2 3
-f 1 3 4
+f 3 2 4

src/Magnum/SceneTools/Test/SceneConverterTestFiles/two-triangles-transformed.bin.in

@@ -1,9 +1,14 @@
 # Like two-triangles.obj, but the second triangle moved 10 units on Y
 type = "3f3f3f 3f3f3f"
 input = [
-    -1,  1, 0,
+    # 2 3--5
+    # |\ \ |
+    # | \ \|
+    # 0--1 4
+
     -1, -1, 0,
      1, -1, 0,
+    -1,  1, 0,
 
     -1, 11, 0,
      1,  9, 0,

src/Magnum/SceneTools/Test/SceneConverterTestFiles/two-triangles.obj

@@ -1,11 +1,11 @@
-# 1 4--6
+# 3 4--6
 # |\ \ |
 # | \ \|
-# 2--3 5
+# 1--2 5
 o First
-v -1  1 0
 v -1 -1 0
 v  1 -1 0
+v -1  1 0
 f 1 2 3
 o Second
 v -1  1 0