Previously only network errors could cause a restoration of a session,
but now a BYE response sent by the server can also trigger it.
An option has been also added to control if and when the recover
function will be called.
Instead of the account details, a pointer to the C structure is used in
Lua, stored as light userdata.
The 1.x deprecated configuration format has been removed, partly due to
the above change, and partly because it has been included for long
enough now.
Move the source code to the src dir, the man pages to the doc dir, and
the example configuration files to the samples dir, and update all
relevant files to reflect the changes.