Replace go mod vendor with go mod download everywhere

Use sudo on make clean instead of make vendor

Remove all references to master in the readme

Sort the messages based on timestamp

Instead of depending on chat.db row ordering, actually sort by the
timestamps in the chat_message_join table.

Fixes #9

Update short flags

Fixes #6

Add success message

Improve error message when using default DBPath

Add vendor makefile target

Reorder options

Move ExportChats to package main