add typedef for "double"

```
struct Point {
  double x, y;

maybe add "config.h"

typedef double Float;

and

struct Point {
  Float x, y;

Many enough "float" accuracy

Tnx

P.S. Sorry for my google translate english ^^
```

Original issue reported on code.google.com by `levchenk...@gmail.com` on 6 Mar 2014 at 11:58
