Also pass in context as an argument to acclogp!!

[torfjelde]

Some samplers have very specific ways of accumulating log-probabilities which they do through overloading of the tilde-pipeline, e.g. PG in Turing overloads both assume and observe because it needs to accumulate the log-probabilities in the task local varinfo rather than the "global" varinfo.

But this means that, in certain scenarios, e.g. PG, usage of @acclogprob!! in a model will (silently) result in target the incorrect model!

One way we can fix this is to also pass in the context to @acclogprob!! (and acclogp!!), which can then alter how the log-probs are accumualted.

A few examples where this is useful:

• Particle samplers from AdvancedPS.jl, e.g. PG in Turing.jl, can then correctly handle @addlogprob!! by accumulating the log-probabilities in the task-local varinfo rather than the "global" varinfo.
• We can remove some hacks used in particle samplers that break composability with other contexts; in particular, instead of accumulating log-probs in the assume and returning 0 instead of the actual logp value (as is done here: https://github.com/TuringLang/Turing.jl/blob/6649f10c48917a27531214f02777408d2ab82928/src/mcmc/particle_mcmc.jl#L376), we can simply return the logp value as we do in all other implementations of assume and let the acclogp!! call in tilde_assume handle the accumulation to the task-local varinfo. This would then make particle samplers compatible with stuff like re-weighting of log-probabilities, e.g. using MiniBatchContext or the GibbsContext in New Gibbs sampler using condition Turing.jl#2099 which overrides the assume statements to instead return a conditioned value + its logprob, while avoiding hitting the observe.

[github-actions]

Pull Request Test Coverage Report for Build 6923549774

• 11 of 11 (100.0%) changed or added relevant lines in 3 files are covered.
• 33 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.04%) to 80.284%

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Files with Coverage Reduction	New Missed Lines	%
src/utils.jl	33	82.28%

Totals
Change from base Build 6906848787:	0.04%
Covered Lines:	2541
Relevant Lines:	3165

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💛 - Coveralls

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c9489aa) 80.24% compared to head (1cfe231) 80.28%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #563      +/-   ##
==========================================
+ Coverage   80.24%   80.28%   +0.03%     
==========================================
  Files          25       25              
  Lines        3159     3165       +6     
==========================================
+ Hits         2535     2541       +6     
  Misses        624      624              

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[yebai]

Thanks @torfjelde -- this looks good. Shall we make this release breaking?

[torfjelde]

AFAIK it's not breaking; we're still keeping the old acclogprob!! definition too.

EDIT: bumped patch version