params: review locks implementation

[vitreo12]

The current implementation stores an array[2, float] for each param and a global params_lock.

In the perform block, if lock is acquired, the first entry of the param is used. Otherwise, the second (which is updated whenever a successful lock occurs).

Would an implementation with each param being an Atomic[float] be faster? This would need testing.

[vitreo12]

Using a new object, Omni_Param