Solution write request

[ssriram1992]

Can we have a feature to writeSolution for innerApproximation or combinatorial PNE?
The option could be to enter

1. An unsigned int k indicating the frequency of writing the iteration log.
2. Choice of whether one needs separate file for every k iterations or same file(appended) or same file overwritten thus containing only the latest two iteration's details
3. An option to not write any intermediate logs except for console printing (as it is right now)
4. If we have intermediate NE and feasible deviations in the innerApproximation, print how better is the value of this deviation.

This could be particularly useful in examining what is happening, when the algorithm terminates due to timeLimit or numerical issues.

[ssriram1992]

To be clear - I am referring to writing the file Solution.txt and Solution.json at the end of each iteration (or alternatively Solution_iter_i.json if different file for each iteration)

[ssriram1992]

Additional request - please can we have these changes in the master branch?