str_case_x deprecated

[ifarup]

Compiling with a recent LaTeX version causes an error due to the deprecation of 'str_case_x' in the LaTeX3 libraries. I haven't figured out the details, but i think it should be substituted with 'str_case_e' with the appropriate options (nnT, nnTF etc.).

[SteffenBakker]

Same issue here. The suggested substitution with 'str_case_e' did the trick for me.