disallow removal of rtable 0; this table is always present

[smytht]

Testing worked as expected (once I had specified rtable 0 ) in nsh... but before i explictly entered rtable 0

i got a different error no % rtable 0 does not exist in database perhaps this is because I had not initialised nsh properly ? (building nsh and runing it on my dev machine...
but the logic seems dependent on an explict declaration of rtable 0 ... where it should be implicitly declared... (and the nsh db should have it ...

• suggest % cannot remove rtable 0 be changed to % cannot remove the main rtable, rtable 0
  see test script below...

nsh(config-p)/no r route rtable nsh(config-p)/no rtable 0 % rtable 0 does not exist in database nsh(config-p)/rtable 0 nsh(config-p)/ nsh(config-p)/ nsh(config-p)/no arp editing ip6 pipex bridge group mpls route configure interface nameserver rtable ddb ip ndp verbose nsh(config-p)/no arp editing ip6 pipex bridge group mpls route configure interface nameserver rtable ddb ip ndp verbose nsh(config-p)/no r route rtable nsh(config-p)/no r route rtable nsh(config-p)/no r route rtable nsh(config-p)/no rtable 0 % cannot remove rtable 0

[stspdotname]

According to chris, rtable 0 is not supposed to be in the database. The above force-push makes sure of this.

[stspdotname]

When testing this make sure to delete /var/run/nsh.db if it contains rdomain 0. I suppose nsh should update the table to delete such rows if it finds any?

[stspdotname]

Closed and merged into pr 118 instead.