v0.1.0 estimateW

• Added new dataset: nuts1growth.
• Added new function: semw() and sdmw() for handling spatial error models.
• Corrected labeling of sigma to sigma2 in results.
• Added option to sim_dgp() for supplying an exogenous spatial weight matrix (defaults to NULL).

v0.0.1 estimateW

• First CRAN release version.
• Prepare for release with basic functionality
• R CMD check --as-cran: No errors or warnings, one note (New submission)