ids should be represented by different types

[swizzard]

currently, HastodonId represents status ids, account ids, and media ids. it would be more informative to have separate types for each of these. additional type-safety could be guaranteed by having these be newtypes.

the downside of this would be a little more noise in the API functions that use replace, but we could avoid this by using a custom function IsString a => a -> a -> a -> a and deriving IsString for our newtypes.

[syucream]

It might be fixed by #27