Introducing string object.

pub/lib/CMakeLists.txt

pub/lib/fbase.cpp

pub/lib/fregistry.hpp

pub/lib/fstring.cpp

pub/lib/node.cpp

pub/lib/obj.hpp

pub/lib/ptr.hpp

pub/lib/toplevel.cpp

pub/lib/xax_lex.lpp

pub/lib/xax_yacc.ypp