Highs_setOptionValue unimplemented

[matbesancon]

I don't find any implementation of the Highs_setOptionValue function, which is only defined in the C interface but not in the shared object.

[mlubin]

@jajhall, d23eca2 appears to have addressed this issue. Should we start adapting the Julia wrapper or should we wait for more changes?

[jajhall]

I didn't create a full set of getters and setters in the C interface. HiGHS has options of bool, int, double and string type. There are still only setters for int, double and string (as char*), and getters for int and double. I'm afraid my C/C++ skills aren't up to the others. Note that we created setHighsOptionValue in the C interface when we were going to pass all values of options as strings. In the C++ interface we now we allow them to be passed as bool, int, double, string by overloading the definition of setHighsOptionValue. In the C interface I created setHighsIntOptionValue, setHighsDoubleOptionValue and setHighsStringOptionValue to achieve the same functionality, leaving setHighsOptionValue rather than delete it from the API. I'll get @feldmeier on the case to do a proper job, but opinions from others would be welcome.

[feldmeier]

I added the getter/setter for bool and the getter for string options in #299. For retrieving a string option the user needs to provide a pointer to a sufficient amount of memory. There is no good way of handling the memory allocation for the user in this case.