Working on the backup log viewer.

Basically the idea for the log is to support multiple detail levels, each capturing progressively more context that its parent.

With all details collapsed, the log gives a quick overview of when the job was running and if it completed OK or with errors.

Expanding details allows for a drill-down - to look at the details such as the file and byte counts, the timing and performance data and the details of any errors that have occured.

I'm still going to shuffle things around the window, e.g. push the -/+ buttons to the right, tweak the styling too, but the general hierarchical format will stay. It is a very convenient way of organizing the log info.