lazycat/proxies/: Rename to `lazycat/proxy/'

* lazycat/proxies/: Rename to `lazycat/proxy/'.
* lazycat/proxy/ssh-proxy.scm, lazycat/proxy/tcp-proxy.scm: Move
  to `(proxy ssh-proxy)'.
* lazycat/daemon/proxy-list.scm: Update.
* lazycat/Makefile.am (SUBDIRS): Update.
* configure.ac: Update.