helske/bssm: CRAN release 1.1.7-1

New CRAN version with mostly internal tweaking and more examples:

• Fixed an error in automatic tests due to lack of fixed RNG seed.

• Added a function cpp_example_model which can be used to extract and compile some non-linear and SDE models used in the examples and vignettes.
• Added as_draws method for run_mcmc output so samples can be analysed using the posterior package.
• Added more examples.
• Fixed a tolerance of one MCMC test to pass the test on OSX as well.
• Fixed a bug in iterated extended Kalman smoothing which resulted incorrect estimates.