switch to coroutine execution model

TODO.md

@@ -1,13 +1,18 @@
 ## General
 
 - Make UI strings localizable (e.g. entries in menus, welcome message, etc.)
-- Add an idle connection timeout for proxy sessions
 - Clean up ItemParameterTable implementation (see comment at the top of the class definition)
-- Handle MeetUserExtensions properly in 41 and C4 commands on the proxy (rewrite the embedded 19 command and store a map of received destinations)
+- Handle MeetUserExtensions properly in 41 and C4 commands on the proxy (rewrite the embedded 19 command and put some metadata in the persistent config, perhaps)
+- Make a server patch version of story flag fixer quest
+- Make proxy server handle all login commands, including sending 9C when needed
+- Add $switchit command (activates switch flag(s) for nearest object, e.g. laser fence, door, fog collision)
+- Add a way to persist flags across connections, at least on v3, because of Meet User + B2 enable quest interactions - maybe update the quest to patch one of the login commands so the server can tell it's enabled
+- Handle items in crossplay - use the replacement table
 
 ## PSO DC
 
 - Investigate if https://crates.io/crates/blaze-ssl-async can be used to implement the HL check server
+- v2 challenge data in $savechar/$loadchar doesn't work properly
 
 ## Episode 3
 
@@ -27,3 +32,5 @@
 - Figure out why Pouilly Slime EXP doesn't work
 - Make server-specified rare enemies work with maps loaded by the proxy
 - Implement serialization for various table types (ItemPMT, ItemPT, etc.)
+- Record some BB tests
+- Add all necessary Guild Card number rewrites in BB commands on the proxy