Fix $/ being interpolated into a regular expression

[Corion]

File::Slurp doesn't guard against $/ being set to something that looks like a regular expression. This fixes that by quoting the contents of $/ unless paragraph mode is on.

This doesn't guard against

$/ = \1024;

but that's not really relevant I presume.

[genio]

@Corion Please accept my apologies in advance. Right now, we're focused solely on getting 5.30 compliance with the binmode + sysread/write/open problem. Once that is sorted, we'll happily come back around to enhancements.

I'll leave this open here, but it likely won't be reviewed/merged until after the aforementioned fixes happen.

[Corion]

Thank you very much!

I don't mind if the change gets delayed - I'm waiting since 2012 for fixes on Windows ( See https://rt.cpan.org/Public/Bug/Display.html?id=84918 ), so I'm really happy that anything is moving at all with File::Slurp.

My change here isn't necessary to keep working programs from breaking.

[Corion]

I've fixed the merge conflict to track development and restructuring.

[genio]

Please rebase this when you get a chance and we'll start reviewing. Thanks!

[Corion]

I've rebased it just now

Thank you for looking after the module!