Source directivity

Sound source directivity patterns are the newest (and possibly last, for a while) feature to be added to the ViMic project. The user will be able to load or draw a directivity pattern in a Max table object. The ViMicMax~ external will use this table to obtain a directivity gain value. It remains to be seen whether or not the source object should have its own copy of the table, or alternately use a built-in function to read individual values from the table.