texturev: Added .pgm and .ppm extensions as supported.

tools/texturev/texturev.cpp

@@ -75,7 +75,9 @@ static const char* s_supportedExt[] =
 	"jpeg",
 	"hdr",
 	"ktx",
+	"pgm",
 	"png",
+	"ppm",
 	"psd",
 	"pvr",
 	"tga",