Allow passing a string reference of source to PPI::Dumper->new

[moregan]

Request from the RT queue: https://rt.cpan.org/Public/Bug/Display.html?id=16836 -- support passing source code into PPI::Dumper->new, rather than first having to create a PPI::Element:

In addition, it would be cool if PPI::Dumper could allow the following style in addition: 

# Create the dumper from a code ref
my $Dumper = PPI::Dumper->new( \'$a = 1;' );

[wchristian]

@adamkennedy : In the RT ticket you indicated you took the ticket. Did you end up doing something with this?