add libev to the README
add libev to the README

Ignore-this: 93129e7759d12ac5803c2294f91c6ccb

darcs-hash:20101216164619-c41ad-26f719131d827657e92720189b3d956de2343113

ocsigen/lwt,mfp/lwt,rgrinberg/lwt,mirage/lwt,rneswold/lwt,rneswold/lwt,c-cube/lwt,rgrinberg/lwt,ocsigen/lwt,ocsigen/lwt,rgrinberg/lwt,rneswold/lwt,rgrinberg/lwt,janestreet/lwt-async,fdopen/lwt,c-cube/lwt,fdopen/lwt,janestreet/lwt-async,gfxmonk/lwt,gfxmonk/lwt,mfp/lwt,c-cube/lwt,mirage/lwt