this makes it more verbose what $HomeServer is and is
also technically the correct type for Invoke-RestMethod -Uri,
although we only use it concatinated there
fixes#3
this adds m.room.member to the StateFilter and introduces the function
Join-MatrixRoom
it also introduces an additional hook in Invoke-MatrixSync
next_batch now is saved to account_data and retreived on the first start,
so we don't get already processed events during startup
additionally there now is a huge filter, which extracts only the
events+fields we really need. this prevents problems like e.g. account_data
feedback loops uneccessary syncs because ephemeral events
lub