avoids alloc in PhpString.GetBytes()
avoids alloc in PhpString.GetBytes()

encodes string directly into the underlying byte[] buffer

iolevel/peachpie-concept,iolevel/peachpie-concept,peachpiecompiler/peachpie,peachpiecompiler/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept