Refactor use of Events when generating verbose output

[bmourad01]

From #167, @ivg suggested the following:

I am seeing a lot of Events.(send @@ Info (sprintf fmt x y z..)), which are pretty hard to read and write, so I would suggest you to create an info function analogous to the BAP's info, that will have type, val info : ('a,formatter,unit) format -> 'a so that you can write,

Events.info "The patch has the following BIL: %a" Blk.pps blk;

Here is how to define it,

let info fmt =
  Format.kasprintf (fun msg -> send (Info msg)) fmt

The same functions could be defined for other types of events.

This could be a nice quality of life improvement.