A new rule for automatic reconciliation and a cron [rebased]

A rebased version of https://github.com/OCA/bank-statement-reconcile/pull/7

Discussion continues from there.
Shouldn't it be

    credit_lines + debit_lines,
    credit_lines + debit_lines,

according to https://github.com/guewen/bank-statement-reconcile/commit/279a176e22bcca4db214dae665abafb02cfd672d