merged changes from RC_1_0

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@10598 a83610d8-ad2a-0410-a6ab-fc0612d85776
remove the concept of timeout_extend in piece request timeouts. if a request times out, cancel it as soon as it holds up the completion of a piece

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@10599 a83610d8-ad2a-0410-a6ab-fc0612d85776