Changelog

*_case() functions can now use lists as return values (#7).
*_case() functions no longer perform automatic type conversion on non-atomic return values (#7).
grep_case() and grep_case_fct() now support vectors in the left-hand side of arguments (#8).

Accept named arguments with or without preceding dots, e.g. default or .default (#5).
Take default into account when determining the class of output (#5).
Fix bug where replacement would fail if a condition evaluated to a vector made up of both NAs and FALSEs with no TRUEs.
Improve error messages (#5).
No longer rely on deprecated plu functions (#4).

Added *_case_fct() family of functions
- These work the same as their *_case() equivalents, but return factors
- Factor levels are determined by the order of case statements.
- in_case_fct(x < 10 ~ "Low", x < 20 ~ "Medium", default = "High") returns a factor with levels "Low", "Medium", and "High".
Added *_case_list() family
- These work the same as their *_case() equivalents, but return lists
- This allows the functions to return complex data types that would otherwise be broken by automatic type conversion.
Implemented lazy-ish evaluation of outputs.
- If the LHS of a formula is never true, the RHS is not evaluated.
  - However, the RHS is still evaluated for all inputs if any input is TRUE.
- If condition in if_case() never takes one of the three logical values, the corresponding output is not evaluated.

Added grep_case() which works similarly to switch_case() but uses pattern matching instead of exact matching.
Added fn_case() which applies a function to the input and each formula’s left-hand side to create the logical vectors used by in_case().
Added fn_switch_case() which applies a function to the left-hand side of each formula to create the vectors used by switch_case().

incase (development version)