Linking errors

[mrjackbo]

I was using version 0.1.0 of icecream-cpp for a while, and I have IC statements in multiple source files, which are compiled independently (as cmake object libraries) and then linked together into different binaries and shared libraries. This used to work very nicely. Now I upgraded to 0.3.0, recompiled everything, and get linking errors like so:

multiple definition of `icecream::detail::show_c_string()'

I know that this is potentially an issue with header only libraries in general, but perhaps there is something you can do, as it used to work in previous versions.

[renatoGarcia]

@mrjackbo Fixed. Thanks for catch that!