make sure the types of the PDL data is correct
fixes for Data::Frame comparison
only show the converted R data if equality check failed
add support for converting PDL data to array, vector, or matrix

This adds support for converting PDL data to an R array (n-d), vector
(1-d), or matrix (2-d) and preserves the type (double/numeric or
long/integer) correctly.

Closes <https://github.com/zmughal/embedding-r-in-perl-experiment/issues/12>.