made some thing in mani.grammar non-optional

psGrammar/tasks/manipulation/manipulationTask.jsgf

 #JSGF V1.0;
 grammar manipulationTask;
 
-public <navigation> = (tobi | biron) [please] ( [clean the] <shelf> | [clean the] <table>);
+public <navigation> = (tobi | biron) [please] ( clean the <shelf> | clean the <table>);
 
 <shelf> = (shelf);
 <table> = (table);