perldiag: Consistent spaces after dots
G_METHOD_NAMED flag for call_method and call_sv

Can be used when it's known that method name has no
package part - just method name.

With flag set SV with precomputed hash value is used
and pp_method_named is called instead of pp_method.
Method lookup is faster.
SV_CONST(name) and PL_sv_consts

SV_CONST(XXX) returns SV* that contains "XXX" string.
SVs are built on demand and stored in interp's structure
for re-use. All SVs have precomputed hash value.

Creates SVs on demand, we don't want 35 SV created during
compile time or cloned during thread creation.
change magic_methcall to use SV with shared hash value

Perl_magic_methcall is not public API, so there is no
need to add another function and we can just change
function's arguments.
change tied_method to use SVs with precomputed hash values