Don't use std::function

[Eyal Rozenberg]

std::function is a heavy container, whose main use is encapsulating potentially complex invokable objects. See this discussion; why use it? A simple (typed) function pointer should probably do nicely.

[Martin Olivier]

Hello, I just made your requested changes on #21
Feel free to make a review on those changes, after what i will merge them

[Martin Olivier]

Hello,

I made new changes on #21

I removed get_function and get_variable and replaced them with get_symbol instead:
T &dylib::get_symbol<T>(const char *)

This will do the job for both functions and variables.

I also updated the documentation regarding that.

I think this way will be cleaner but I would like to have your opinion on that.

Since we will need to make breaking changes with this issue (#18) it would be an opportunity to do the same regarding this

[Eyal Rozenberg]

I am actually not entire sure that it's better to "roll everything up" into a single function. It has some elegance benefit, but what if, in the future, you wanted to differentiate their behavior somehow? But maybe that's not interesting/not relevant. Like I said, no strong opinion.

[Martin Olivier]

Hello,
Finally, i kept the original names get_function and get_variable to be able to make specific variable / function mangling for this issue #27.
get_function now returns a function reference instead of an std::function

Merged into dev branch at a3ef5e7