Removing someone from a trip leaves their payer and split rows on the
expenses they were part of. Every save ran the ids the form sends back
through the roster filter, so an unchanged save dropped them, total_price
shrank to what the rest had paid and a custom split stopped adding up.
Ids already on the expense now stay allowed, as payer or as member, and
can still be taken off it on purpose. A new expense and an id that never
was on the expense are filtered as before (#1952). The paid ticks of the
split carry over a form save instead of being reset. REST, the plugin RPC
and the MCP split checks all read the same allowed set from the service.
Refs #2604
Maurice
af66bdd910