Revision of handling of frameoffset for NPH, SPH
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...
Addition to earlier: Fix monstro
Sample-exact models: improve
- Remove the redundant hasSampleExactData() function. Instead, signal lack of s.ex.data by returning a NULL in valueBuffer()
- Cache s.ex.buffers and only update them once per period
- Make valueBuffer() in AutomatableModel threadsafe so that it can be used for NPH's sharing the same model
- Add sample-exactness to instrumenttrack's vol & pan knobs
Merge pull request #911 from diizy/master-nph

Revision of handling of frameoffset for NPH, SPH