Add version to header

[aggsol]

I usually copy the header into my projects but it is hard to track which version it is. How about adding a #define RANG_VERSION to it?

[kingseva]

It's also good idea to add version/about functions that returns version string and short description of the library.

[agauniyal]

@aggsol would -

#define RANG_VERSION_MAJOR 3
#define RANG_VERSION_MINOR 1
#define RANG_VERSION_PATCH 0

format fine for you?

@kingseva why not constexpr members inside rang:: namespace 😛

cout << rang::version << rang::description;

though I don't know if people really use versions like this 🤔. Anyways I'll add both in next version 👍

[aggsol]

@agauniyal Fine for mie, I just need a way to manually check what version a header is.

[agauniyal]

Added for next-release.

[kingseva]

I think it will be more convenient to place version macros is on top of the header not on the bottom 😄. Most of developers don't like to scroll down headers to see witch version of header they addded to the project.

Also it's handy to use check version macros:

#include <iostream>

#define RANG_VERSION_MAJOR 4
#define RANG_VERSION_MINOR 0
#define RANG_VERSION_PATCH 0

#define RANG_VER_CHECK(major,minor,patch) (((major) << 16) | ((minor) << 8) | (patch))
#define RANG_VER RANG_VER_CHECK(RANG_VERSION_MAJOR,RANG_VERSION_MINOR,RANG_VERSION_PATCH)

int main()
{
#if RANG_VER >= RANG_VER_CHECK(4,0,0)
    std::cout << "Hello, rang 4 !\n";
#endif
}