Contributions are welcome!


* [NEW FEATURE] TODO... #81 number format

* [NEW FEATURE] TODO... #477 sprintf localised number format

* [NEW FEATURE] TODO... #471: split into overlapping or non-overlapping chunks,
    possibly of different lengths

* [NEW FEATURE] TODO... #445 stri_dup: add sep argument

* [BUILD TIME] TODO.. Tomas Kalibera suggests to use the Rtools version of ICU
    for Windows: "Rtools43 has icu 72.1, Rtools42 has 71.1."; see also some notes
    in configure.ac

* [LATER] compress, move, remove src/icu55/data/*, src/icu61/data/*,
    and src/icu69/data/*; currently, the *.dat files may still be downloaded
    by old R/install.R files.
