dev: update to roxygen 4.0.2
dev: move tests to tests/testthat
test that abs2rel work for >1 file
dev: tell rstudio to use devtools
remove warning in abs2rel when >1 path
Proper warning/errors when >=1 out of >1 wrong
zipinfo quotes input paths

* to avoid trouble with spaces etc
* thought system2 handled this somehow, but does not
* closes https://github.com/jefferis/nat.utils/issues/3
Bump version to 0.4.3