message: Change version to 0.5
diff: /**
  - * meshoptimizer - version 1.0
  + * meshoptimizer - version 0.5
  *
  * Copyright (C) 2016-2017, by Arseny Kapoulkine (arseny.kapoulkine@gmail.com)
  * Report bugs and download new versions at https://github.com/zeux/meshoptimizer
  #include <stddef.h>
  // Version macro; major * 100 + minor * 10 + patch
  -#define MESHOPTIMIZER_VERSION 100
  +#define MESHOPTIMIZER_VERSION 50
  // If no API is defined, assume default
  #ifndef MESHOPTIMIZER_API
  