There are 2 uses of all_msg_list previous to this commit:
(1) The contiguous block of messages to be used for constructing the
initial state of narrows.
(2) A way to look up an arbitrary message by ID that may or may not be
in the home view to check if we have it locally.
We eliminate all applications of use case (2), replacing them with
queries on message_store, since they are in fact wrong -- any messages
that are outside the contiguous time period of all_msg_list would not
appear in all_msg_list and thus would incorrectly not be returned.
(imported from commit e2e2efe919242331bbc44abc6c50b16e3ab1336e)
This implementation is somewhat hackish in large part because I think
we're going to be wanting to redo the get_old_messages API somewhat
soon, and this may naturally become a lot cleaner as a result, but
this isn't a lot of code and fixes#2235 part (A) and substantially
mitigates #1510.
(imported from commit 47a2160a44befa9d83190c5cc95b90e92cc5b4cc)
I apparently screwed up when backing up the process_loaded_for_unread
move in a way that just lost the function.
(imported from commit 91dfcf1abc85d439274cb8b0be380e9230942ebb)