Make runsolver optional

I am currently trying to use [aclib2](https://github.com/DE0CH/aclib2.git), which depends on GenericWrapper4AC. But since I mainly use a mac for development, it would not run. I guess it would be similar for folks using Windows.

I have yet to found an alternative for limiting and measuring memory and cpu usage on Mac, so I wonder if there's a way to hack this to make it work. Since during development, getting the statistics is less important than getting it to run, could we, for example, run the algorithm without any memory and time limit, and always return `1` for memory and cpu usage so that packages that expect a positive floating point number would not break.