How do clients avoid downloading the whole memberlist when viewing a moderated room where most of the participants are viewers? (SPEC-109)

The equivalent of 'conference' mode on IRC servers - where you can't see who else is listening in on the room; you can only see the handful of people with permission to talk.

This presumably means
- adding a power level below which participants aren't shown in the membership list
- adding a power level above which participants are shown in the membership list if desired

or, just a way to filter/unfilter the membership list based on powerlevel?

(Imported from https://matrix.org/jira/browse/SPEC-109)

(Reported by @ara4n)

No file or test is named. Start by reviewing the Matrix room-membership and power-level specification, then compare the requested behavior with IRC conference mode. Done means the membership-list filtering rules and visibility controls are fully defined for the protocol.

Written by the indexing model from the issue text.