MB-8689 Add API to get list of indexed seqs per view group

Change-Id: I5f07990fd34a7ba6ac2ceda1c0f674c4592d2ddc
Reviewed-on: http://review.couchbase.org/28057
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>
MB-8780: added compactor option to avoid purging too new seqnos

Change-Id: Ibb3fd6702573220f7e1de4d31f0b5286f202e8ae
Reviewed-on: http://review.couchbase.org/28035
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aaron Miller <apage43@ninjawhale.com>
MB-8677 Ignore unindexable replicas on transfer set to active

Replicas on transfer look like normal active partitions
for the caller. Hence they can be marked as unindexable.
The actual transfer to a real active partition needs to
happen though. Thus an intersection between newly activated
partitions and unindexable ones is possible.

Change-Id: I8b36741f0d25f9a902a78c113c38d23042010d8e
Reviewed-on: http://review.couchbase.org/27803
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>
MB-8677 Improve test coverage

Add assertion for the exact condition that triggered an error
in MB-8677.

Change-Id: Iae29ff79cfeee413777a7dae223a85c1276c658d
Reviewed-on: http://review.couchbase.org/28110
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>
MB-8877 Fix builtin reduces for subset development views

The regression was introduced in the commit
912b8667560a275a652a2ff0d9d9264ed38e9328:

"MB-7978 Fixes to view tree with multiple reducers"

It only affects 2.1.0, 2.1.1 and 2.2.0 releases. The 3.0 (master branch)
is unaffected, because the same view engine is used for both development
and production views, unlike previous releases.

Change-Id: Id2161d98b015a4fb8a841ded38affad31e4a8c56
Reviewed-on: http://review.couchbase.org/28429
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Merge remote-tracking branch 'origin/2.1.1'

* origin/2.1.1:
  MB-8877 Fix builtin reduces for subset development views
  MB-8677 Improve test coverage
  MB-8677 Ignore unindexable replicas on transfer set to active
  MB-8780: added compactor option to avoid purging too new seqnos
  MB-8689 Add API to get list of indexed seqs per view group

Conflicts:
	src/couch_set_view/src/couch_set_view.erl

Change-Id: I3655f5bad25d178d3a5d29bfa6b838e89fb6a916