Allow local symbols to be referenced

Local symbols can now be referenced outside the scope of their parent, by using the syntax “Parent.Chlid”.

- Local symbol names are now stored internally as “Parent.Child”.
- The symbol’s scope field no longer forms a linked list of the prior local symbols; it will now always contain the parent.
- Add the ability use EXPORT and GLOBAL with local symbols.
- Reduce duplication between findsymbol() and findpsymbol(), as well as between sym_AddLocalReloc() and sym_AddReloc().

src/asm/asmy.y

@@ -587,7 +587,11 @@ label : /* empty */
 		else
 			sym_AddReloc($1);
 	} | T_LABEL ':' ':' {
-		sym_AddReloc($1);
+		if ($1[0] == '.') {
+			sym_AddLocalReloc($1);
+		} else {
+			sym_AddReloc($1);
+		}
 		sym_Export($1);
 	};