starting with perl 5.18.0 the core Pod::LaTeX is deprecated

...in other words, using Pod::LaTeX as installed by the perl core
is deprecated.  Pod::LaTeX may well enjoy a long full life outside
of the core.

Users will be warned to please install Pod::LaTeX from the CPAN.
do not install to core, starting with perl v5.12.0

For one thing, v5.12.0 fixed the ordering of @INC so that site comes
before core and things installed to site from the CPAN will be
correctly loaded before the version from core is found.

For another, the install destination will need to be site to make the
CPAN-installed Pod::LaTeX not trigger deprecation warnings!
Merge pull request #1 from rjbs/master

deprecate use of Pod::LaTeX from core