nbody.pl: parse while, -expr, ...

special case: for"|"foreach"|"while"|"class"|"if"|"elseif with list block to be handled in the compiler
parse use v5.10
++G->lineno at end-of-line, and omit \r\n from utf8
eval use|no immediately: use|no, name, args..., special case use|no p2;
rewrite nbody.pl to be parsable by p2