bgpd: Add new configuration cli for eBGP and iBGP multipath.
There is support to configure this for each (AFI,SAFI), but
currently this configuration is only present for IPv4 unicast:

 maximum-paths [ibgp] <1-255>
 no maximum-paths [ibgp] [<1-255>]

* bgpd/Makefile.am
  * Add bgp_mpath.h and bgp_mpath.c to build
* bgpd/bgp_mpath.h
  * New file for bgp multipath declarations
  * define BGP_DEFAULT_MAXPATHS
* bgpd/bgp_mpath.c
  * bgp_maximum_paths_set(): Configure maximum paths for the given
    afi, safi and bgp instance
  * bgp_maximum_paths_unset(): Return maximum paths configuration to
    the default setting for the given afi, safi and bgp instance
* bgpd/bgp_vty.c
  * Define command strings for above CLI
  * bgp_config_write_maxpaths(): Outputs configuration for the given
    afi, safi and bgp instance
  * Install command elements for IPv4 unicast
* bgpd/bgp_zebra.h
  * bgp_config_write_maxpaths(): External declaration
* bgpd/bgpd.c
  * bgp_create(): Initialize bgp instance to default maximum paths setting
  * bgp_config_write_family(): Output maximum paths configuration
    for the given address family
  * bgp_config_write(): Output maximum paths configuration for
    IPv4 unicast address family
* bgpd/bgpd.h
  * struct bgp: Add storage for maximum paths configuration for
    each afi, safi
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index ee0cc5d..e86fca3 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -57,6 +57,7 @@
 #include "bgpd/bgp_advertise.h"
 #include "bgpd/bgp_network.h"
 #include "bgpd/bgp_vty.h"
+#include "bgpd/bgp_mpath.h"
 #ifdef HAVE_SNMP
 #include "bgpd/bgp_snmp.h"
 #endif /* HAVE_SNMP */
@@ -1947,6 +1948,8 @@
 	bgp->route[afi][safi] = bgp_table_init (afi, safi);
 	bgp->aggregate[afi][safi] = bgp_table_init (afi, safi);
 	bgp->rib[afi][safi] = bgp_table_init (afi, safi);
+	bgp->maxpaths[afi][safi].maxpaths_ebgp = BGP_DEFAULT_MAXPATHS;
+	bgp->maxpaths[afi][safi].maxpaths_ibgp = BGP_DEFAULT_MAXPATHS;
       }
 
   bgp->default_local_pref = BGP_DEFAULT_LOCAL_PREF;
@@ -5117,6 +5120,9 @@
 	    }
 	}
     }
+
+  bgp_config_write_maxpaths (vty, bgp, afi, safi, &write);
+
   if (write)
     vty_out (vty, " exit-address-family%s", VTY_NEWLINE);
 
@@ -5290,6 +5296,9 @@
 	    bgp_config_write_peer (vty, bgp, peer, AFI_IP, SAFI_UNICAST);
 	}
 
+      /* maximum-paths */
+      bgp_config_write_maxpaths (vty, bgp, AFI_IP, SAFI_UNICAST, &write);
+
       /* Distance configuration. */
       bgp_config_write_distance (vty, bgp);