Bug 1629

Overview
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The hello implementation currently has a few behaviors that may not be ideal:

- Hellos are always sent by a node, regardless if node is participating in an active route (bug 1188) or not
- Other features in AODV RP are interacting with hellos that should not like RecvRequest and SendRequest (bug 1193) although this has been turned off
- Hellos are not suppressed if there was a recent broadcast (bug 1190, it was in this bug that the suggestion was made to disable hellos by default if the change could be validated)

Hellos have a requirement level of MAY in RFC (see 6.9.).

Patches
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I have a few patches to propose.  I ran the aodv test across all of them and they all passed.  I monitored the behavior of a modified aodv.cc example program to determine behavior changes and have found some behavior that lead me to develop several patches.  

1) Disable hello by default
2) Disable hello by default, and remove the conditional statement on hello bool in the constructor
3) Disable hello by default, and move the action of the conditional statement from the constructor to start method

Build 
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This is the dev build I tried the patches on

andrew@ubuntu:~/repos/ns-3-allinone/ns-3-dev$ hg summary
parent: 9694:eb7335c2423c tip
 add virtual destructor
branch: default
commit: 89 unknown (clean)
update: (current)

Ubuntu 10.04