#1 support for exceptions

[Bérenger Morel]

Currently, pluma-framework uses a C-style way to report errors, which is not really convenient: we need to check if there were an error, and we can not intercept easily the error message.

Using exceptions could fix those problems by adding useful informations about the error.
As a hint, there are:
_ std::exception
_ std::logic_error
_ std::runtime_error
which are pretty easy to us.

I may contribute such support, if you agree that this would be an enhancement.