Allow mysqlbinlog to read gzip files

A common technique is to compress binlog files once all the slaves have ready them. This allows DBA's to keep much more data around for point in time recovery. Typically binlogs compress 10x with gzip. I propose adding an option to mysqlbinlog so it can natively ready .gz binlogs without having to unzip all the files. Even better if the server could read these files and decompress them to send to slaves that may need them.