Address exception classes for user vs. program errors

[restenb]

This PR fixes #782 by changing to std::runtime_error where the cause is incorrect configuration in the XMLs.

While that squashes one loose chicken, a cursory glance at the codebase reveals several other places that could use similar changes. For instance, std::invalid_argument exceptions still abound in scenario_parser.cpp. And there probably are other places where std::out_of_range or std::logic_error may be dubiously applied.

[kyllingstad]

LGTM