Proposal: To add a version number

[djipi]

The version number could be useful when programming with the library, to display it on the usage of a tool by example.
Version number (major, minor, patch) can be on the form of a function or defines.

[brglng]

I will add a version number when I consider the library is stable enough to be tagged with a beta version number. Anyway I don't have too much time to do frequent update to this library, though I will keep the maintenance.