Made the modification methods (.e.g remove, clear) check that the list is not immutable.
Made the modification methods (.e.g remove, clear) check that the list is not immutable.

xcv58/polyglot,xcv58/polyglot,blue-systems-group/project.maybe.polyglot,liujed/polyglot-eclipse,xcv58/polyglot,liujed/polyglot-eclipse,blue-systems-group/project.maybe.polyglot,xcv58/polyglot,liujed/polyglot-eclipse,blue-systems-group/project.maybe.polyglot,liujed/polyglot-eclipse,blue-systems-group/project.maybe.polyglot