#define JCV_SQRT sqrt when using double

[yoavmil]

First of, I used you library and it works great out of the box!

When using double, and not doing #define JCV_SQRT sqrt, gives warnings. you just missed it in the readme.md.

also a couple of feature requests, I could do some if you want:

• let the user define JCV_REAL_TYPE double/float, and hide all other macros under the hood.
• have a c++ wrapper, replacing the array pointer with std::vector etc.
• support segments in addition to points - this is a big request.

[JCash]

Thanks for using it!

I'll add JCV_SQRT to the docs!

1. Sounds like a good suggestion

2. Not sure why a C++ wrapper is needed, I think it will only obfuscate the data.
   Not to mention slow things down, and add code size and complexity.

3. Yes, I've thought about that, but I'm afraid it's such a big task, that I'm most likely never going to have time to add that.