improved SII code.

ec_master_sync_io(); introduced events in the master state machine;
locking of slave scanning and slave configuration through allow_scan
and allow_config flags.

ec_master_calc_addressing(), coupler_index and coupler_subindex variables.
Adapted lsec script and examples.

registration functions now take a slave pointer as argument; changed
values for ec_bus_status_t.

master array; hand ober MAC addresses with array module parameters.

machines, added datagram injection, two different master thread
functions.

pdos_registered flags and pdo_slaves_offline counter.