Vector comonent properties

Added two methods, defineRequiredPropertyVector() and defineOptionalPropertyVector() in PropertyDefinitionContainer, for adding properties for Eigen::Vector types (e.g. Eigen::Vector3f, VectorXd, ...). They take care of providing a factory method, case insensitivity and map the default value. Provided descriptions are appended by a short explanation of property syntax. You can set a delimiter char (space by default). (There is still no dependency to Eigen).

Also made PropertyFactoryFunction a std::function to allow lambdas.

Tested one of my components.

Update: Extended documentation. Merged master into this branch.