Changelog

Update simulate_site_data() function to remove RandomFields package as a dependency.

Fix CRAN note about utils package dependency.
Skip unit tests that require RandomFields package on Windows to avoid spurious failures.

Update prior_probability_matrix() to compute prior probabilities when no existing survey data are available.

Fix issue with fit_xgb_occupancy_models() using more than specified number of threads for parallel processing.
Ensure that PSOCK and FORK clusters used for parallel processing are terminated correctly, even when processing is interrupted.

Fix compatibility issues with updated xgboost package (version 1.5.0).
Fix parallel processing tests given updates to the testthat package (version 3.1.2).
Fix tests for environmental and geographic survey schemes given updates to the gurobi package (version 9.5.0).

GMP dependencies on Windows systems are now handled using RWinLib (see https://github.com/rwinlib/gmp).
Package configuration now reports compilation variables (i.e. PKG_CPPFLAGS and PKG_LIBS variables).
The Free Software Foundation is no longer listed as a contributor and copyright holder because GMP source files are no longer distributed with the package (because GMP dependencies are obtained via RWinLib).
Configuration variables can now (optionally) be used to specify location of GMP and MPFR dependencies for package installation (i.e. GMP_INCLUDE_DIR, GMP_LIB_DIR, MPFR_INCLUDE_DIR and MPFR_LIB_DIR). Although the package configuration routine attempts to deduce these variables automatically, the variables can be used if installation with default settings fails. For example, the variables can be set using the following system command:
```
R CMD INSTALL --configure-vars='GMP_INCLUDE_DIR=... GMP_LIB_DIR=... MPFR_INCLUDE_DIR=... MPFR_LIB_DIR=...'
```

surveyvoi 1.0.6