Add test OBJ containing various number formats.

test/models/OBJ/number_formats.obj

@@ -0,0 +1,23 @@
+v 0 0 0
+
+v 1 2. 3.0
+v +1 +2. +3.0
+v -1 -2. -3.0
+
+v 1e2 2.e1 3.1e2
+v +1e2 +2.e1 +3.1e2
+v -1e2 -2.e1 -3.1e2
+
+v 1e+2 2.e+1 3.1+e2
+v +1e+2 +2.e+1 +3.1+e2
+v -1e+2 -2.e+1 -3.1+e2
+
+v 1e-2 2.e-1 3.1-e2
+v +1e-2 +2.e-1 +3.1-e2
+v -1e-2 -2.e-1 -3.1-e2
+
+v 1e10 2.e01 3.1e10
+
+v 1E2 2.E1 3.1E2
+
+f 1 2 4