improve DHT bootstrapping and periodic refresh

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10463 a83610d8-ad2a-0410-a6ab-fc0612d85776
fix dht log parsing script

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10464 a83610d8-ad2a-0410-a6ab-fc0612d85776
simplify bucket splitting logic. remove some unused function and members from the routing table

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10465 a83610d8-ad2a-0410-a6ab-fc0612d85776