Refactored to use templates and allows vectors to be read from settings into a std::vector container

This pull request involves refactoring the code to use templates & specialisation, instead of overloads, which reduces code duplication, and allows easier changes to be made.

The switch to a template based system was chosen to allow reading of comma separated strings into a vector (which type is determined by the user). It also allows writing of vectors to the file.

(Now with only one commit!) :)
@tehnugget I have a question about the block above. Why don't you simply clear() the vector and use push_back()? The content gets overwritten anyway, right.