Free Boundary Coil Optimization

[lazersos]

This adds an ability to STELLOPT to perform free boundary coil optimization. This is sometimes called single stage optimization. To run in this mode, not only must coil optimization be performed but the VMEC INDATA namelist will require LFREEB=T and the user to provide an inital MGRID_FILE which VMEC can use to run. This MGRID file will only be read once and STELLOPT will generate new MGRID files as it runs. This is attributed to the fact that when VMEC reads the INDATA namelist it automatically checks the MGRID_FILE and loads it. If it does not load, the code will set LFREEB=F and then STELLOPT will behave as if fixed boundary optimization is happening.

Please check to make sure non-coil optimization runs are not affected.