Receive/resume support added

Syncoid now supports resumable replication by default when both source and target support receive_resume tokens. Resume support can be manually disabled with new --no-resume argument if necessary. Syncoid also supports passing CLI arguments to SSH now with -o opt1=value,opt2=value syntax, and will continue recursive replication with remaining child datasets when any one dataset errors out (for example, due to being busy at the time, having gotten deleted out from under syncoid, etc).