Update plotting capabilities and dataset restructure

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Features
 
+- [#198](https://github.com/pybop-team/PyBOP/pull/198) - Adds default subplot trace options, removes `[]` in axis plots as per SI standard, add varying signal length to quick_plot, restores design optimisation execption.
+- [#224](https://github.com/pybop-team/PyBOP/pull/224) - Updated prediction objects to dictionaries, cost class calculations, added `additional_variables` argument to problem class, updated scipy.minimize defualt method to Nelder-Mead, added gradient cost landscape plots with optional argument.
 - [#179](https://github.com/pybop-team/PyBOP/pull/203) - Adds `asv` configuration for benchmarking and initial benchmark suite.
 - [#218](https://github.com/pybop-team/PyBOP/pull/218) - Adds likelihood base class, `GaussianLogLikelihoodKnownSigma`, `GaussianLogLikelihood`, and `ProbabilityBased` cost function. As well as addition of a maximum likelihood estimation (MLE) example.
 - [#185](https://github.com/pybop-team/PyBOP/pull/185) - Adds a pull request template, additional nox sessions `quick` for standard tests + docs, `pre-commit` for pre-commit, `test` to run all standard tests, `doctest` for docs.