Edge cases of weird-looking interger-ish strings.

[gugod]

This is related to #103, but a bit more cases. Considering the following test program, running with perl 5.28.1, Mouse v2.5.9. The test program take each strings from @ARGV as $x, and "wash" it with "int($x)" -- which leaves some side-effect inside $x. Then see if it passes Int type constraint.

# x.pl
use v5.18;
use warnings;
use Mouse::Util::TypeConstraints;

my $Int = find_type_constraint 'Int';

for my $x (@ARGV) {
    { no warnings; int($x); };

    if ($Int->check($x)) {
        say " Int\t$x";
    } else {
        say "!Int\t$x";
    }
}

Here's the output when using Mouse::XS

> perl x.pl 1 '-1' '-0' ' 1 ' '  -1 ' 0 00 010 18446744073709551615 1.0 0.1 1.2.3 0.0 0.1.0 0b00 0e 0e0 0e1 1e0 '0 but true' '1 foobar'

 Int	1
 Int	-1
 Int	-0
 Int	 1
 Int	  -1
 Int	0
 Int	00
 Int	010
 Int	18446744073709551615
!Int	1.0
!Int	0.1
!Int	1.2.3
!Int	0.0
!Int	0.1.0
!Int	0b00
!Int	0e
!Int	0e0
!Int	0e1
!Int	1e0
 Int	0 but true
!Int	1 foobar

The output when using Mouse::PurePerl

> MOUSE_PUREPERL=1 perl x.pl 1 '-1' '-0' ' 1 ' '  -1 ' 0 00 010 18446744073709551615 1.0 0.1 1.2.3 0.0 0.1.0 0b00 0e 0e0 0e1 1e0 '0 but true' '1 foobar'

 Int	1
 Int	-1
 Int	-0
!Int	 1
!Int	  -1
 Int	0
 Int	00
 Int	010
 Int	18446744073709551615
!Int	1.0
!Int	0.1
!Int	1.2.3
!Int	0.0
!Int	0.1.0
!Int	0b00
!Int	0e
!Int	0e0
!Int	0e1
!Int	1e0
!Int	0 but true
!Int	1 foobar

Trivial values are consistent, values with leading/trailing spaces and a special value "0 but true" are controversial.

IMHO, the result from Mouse::PurePerl looks intuitively correct and we should change Mouse::XS to match that result -- but I also pondering the counter-argument here.