Snapshot log view: Add help for rsync itemize-changes 11-char output

[aryoda]

Current situation

The Snapshot Log View and Last Log View do contain the cryptic 11-char output of rsync to indicate the reason for an rsync action, eg.:

The meaning of f>..t...... is unclear to normal users.

The meaning of the possible values at each char position is explained in man rsync in the --itemize-changes section
and in a more compact form in this SO post: https://stackoverflow.com/a/36851784

Proposed feature

Add

• either a "Rsync change tracking help" button to briefly explain the possible values

• or provide some kind of "hoover over" functionality that shows kinda "intellisense" help for the 11 chars of the current line the mouse cursor is positioned.

  Alternatively a right-click context menu could work instead...

• or add both above proposals