+ nopt.pas, nadd.pas, i386/n386opt.pas: optimized nodes for adding strings
and constant strings/chars together
* n386add.pas: don't copy temp strings (of size 256) to another temp string
when adding
parsed as unsigned constants (otherwise, $80000000 got sign extended
and became $ffffffff80000000), all constants in the longint range
become longints, all constants >$7fffffff and <=cardinal($ffffffff)
are cardinals and the rest are int64's.
* added lots of longint typecast to prevent range check errors in the
compiler and rtl
* type casts of symbolic ordinal constants are now preserved
* fixed bug where the original resulttype wasn't restored correctly
after doing a 64bit rangecheck
