Fixes#19
This is experimental as it changes the whole concept of a Note - We have
till now always assumed that a Note can have attached metadata. With
this, there is no longer any metadata. So other parts of the application
need to start reacting accordingly. For example the Mardkown Editor
should not allow you to modify the title.
This also makes it easier to implement '.txt' file support.
If that title already exists add an _Num at the end.
This won't change the default for existing users, as our settings system
saves the default value and will just load it the next time. This really
needs to be improved.