evaluate correct selection range.

js/pixl/public/trixl.html

			if (ev.ctrlKey && ev.keyCode == 13) { // ctrl+enter
				if (editor == document.activeElement) {
					var sel = editor.value.substr(editor.selectionStart, editor.selectionEnd);
					var sel = editor.value.substring(editor.selectionStart, editor.selectionEnd);
					eval(sel);
				}
			}