v0.4.2

This realease contains a bugfix and several improvements

If you have used multistart optimizations with a least squares optimizer you should update as quickly as possible.

#412 Improves the output of the fides optimizer among other small changes (@janosg)
#411 Fixes a bug in multistart optimizations with least squares optimizers. See #410 for details (@janosg)
#404 speeds up the gqtpar subsolver (@mpetrosian )
#400 refactors subsolvers (@mpetrosian)
#398, #397, #395, #390, #389, #388 continue with the implementation of tranquilo (@segsell, @timmens, @mpetrosian, @janosg)
#391 speeds up the bntr subsolver