GetProperties and Active operations in IValueProviderT interface

[natan-sinigaglia]

GetProperties:

• allows to collect informations about the item we want to sample.
• we can pass PrepareTime, DisposeTime, ...

Active:

• can be called from the sampler
• extends the clip before and after: from InTime - PrepareTime (collected through GetProperties) to OutTime + DisposeTime
• the sampler call Active operation feeding and enum to describe the state of activation ("Before/Inside/After")
• active function has an integer input which is the activation count (which is stored in the clip_R of the sampler?)