CRAN release v9.4.0

CHANGES OR IMPROVEMENTS

• Fix the 'package_skeleton' function to generate internal C code with
  valid C entry names if the package name contains '.', for example,
  for a package named 'pkg.name'.

• Changed the usage of 'any(is.na(x))' to 'anyNA(x)' in the R code.

• Internal refactoring of the 'distance_matrix' function to reduce
  memory usage.

• Ensure to check for a valid model object after updating model data.

• Moved the enumeration of event types to the header file
  'inst/SimInf.h'

• Fixed problems identified with static analysis of the C code using
  the cppcheck and scan-build tools.

• Added the getter function 'u0' to get the initial compartment state
  of a model.