Modernized RMevents_sample

Brought this function up-to-date by having it output the exact same format/data as RMevents. This will allow seamless integration into other Rainmaker functions.

Also fixed an edge-case bug. I had sample data with samples from outside of the rain data. Now it spits out NA values but keeps a placesholder for that storm so that it can easily be added back to the sample data - e.g., nrow(samples) will be the same as nrow(output)