Halt/Breakpoint handling

[perlindgren]

Problem

We would want simulation to run in different modes, stepping (back and forth) and free-running until some Halt/Break condition is encountered. Now the basic support for clock return is implemented, so we can now think about how free-run until halt should be implemented.

Solution

Add a state to the simulator (indicating the status running : bool).

When a component returns with a Halt or Error then the state should be set to false. This state variable can be altered by the gui. We could either have a new run function in the Simulator, that calls clock or have clock itself be repetitive, either should work.

[onsdagens]

Addressed in #78