ssa.c: Add global variables for max. reconnect attempts and timeout.
ssa.c: Zero reconnect counter after new join.
ssa.c: Add new reconnection case
ssa.c: Add cases for reconnect_max_count and reconnect_timeout = 0
[acm.c,acme.c] Add keepalive configuration parameter to ACM.
acm,distrib: Add reconnect_max_count and reconnect_timeout configuration
parameters.

 reconnect_max_count specifies max. number of reconnection to the
 upstream node. If the number is reached the node rejoins to
 distribution tree and asks for a new parent.
 reconnect_max_count < 0, reconnection is disabled.
 reconnect_max_count = 0, rejoin without reconnection.
 Default value is 10.

 reconnect_timeout specifies timeout (in sec.) between reconnections.
 reconnect_timeout < 0, reconnection is disabled.
 Default value is 10.
ssa.c: Change default values for reconnect_timeout and
reconnect_max_count