Create syntax for inline subs

After loading this module, the 'inline' modifier will be legal for sub definitions, such as:

inline sub foo() { print "Here\n";}

This definition creates a new sub foo with the special property that every time it is called in the normal manner (i.e., by name without a leading ampersand), the VM will insert the body of the sub instead of a call to the sub in the generated code.

In other words, when you write this:

foo();

the VM will turn it into the equivalent of this:

do { print "Here\n";}

When testing simple scripts, Deparse is very useful in debugging:

perl5.19.9 -Mblib -MSub::Inline-MO=Deparse -e 'inline sub foo(){print "Here\n";} foo;'
sub foo {
    print "Here\n";
}
;
;
print "Here\n";
-e syntax OK

(The extra ';'s should not be there; that will be fixed before release).

This is currently just a proof of concept, plenty of open issues ...