use Copy instead of unsafe

src/run.rs

@@ -79,24 +79,18 @@ impl Run{
 		}
 	}
 	pub fn finish(&mut self,time:Time)->Result<(),Error>{
-		//code based on std::mem::replace
-		let dest=&mut self.state;
-		//let's ignore ownership rules for a moment
-		unsafe{
-			let state=std::ptr::read(dest);
-			match state{
+		//this uses Copy
+		match &self.state{
 			RunState::Created=>Err(Error::NotStarted),
 			RunState::Started{timer}=>{
-					let src=RunState::Finished{
+				self.state=RunState::Finished{
 					timer:timer.pause(time),
 				};
-					std::ptr::write(dest,src);
 				Ok(())
 			},
 			RunState::Finished{..}=>Err(Error::AlreadyFinished),
 		}
 	}
-	}
 	pub fn flag(&mut self,flag_reason:FlagReason){
 		//don't replace the first reason the run was flagged
 		if self.flagged.is_none(){