Change in handling of frameoffset for multistreamed instruments and sampletracks.
- Instead of holding the offset for the lifetime of the playhandle, negate the offset in the first period
- Multistream-instruments require some small changes: they have to now check for the offset and accordingly leave empty space in the start of the period (already done in this commit)
- There are possibly optimizations that can be done later
- This change is necessary so that we can have sample-exact models, and sample-exact vol/pan knobs for all instruments. Earlier multistream instruments were always rendering some frames ahead-of-time, so applying sample-exact data for them would have been impossible, since we don't have the future-values yet...
Since addition of automation, controllers etc. the freeze functionality
has been rather broken and thus adds no value anymore. In order to not
confuse users with broken functionality, remove it at all.
Closes#345.
Next big coding style update - this time all PlayHandle classes are
affected. Functions like done() and released() were renamed to
isFinished() and isReleased().
