honour_x0 is not exposed to the C interface #230

Hi,

I am creating an issue here to try to get this thing going.

This issue has been identified in Issue #36 of the Julia Interface (PRIMA.jl). The option honour_x0 is not exposed in the c api, which then impacts the Julia API that uses it.

Basically I would like to be able to use that option with the BOBYQA algorithm through the C or Julia API. I have coded myself a solution which I would like to discuss with the project owners. I am going to open a pull request, but feel free to object and make your own solution.

Thank you,