Add handling for log rotation

[ben-spiller]

Is your feature request related to a problem? Please describe the use case.
For non-cumulocity use cases it's common for log files to be regularly rotated.

This means the all-important startup stanza will be present in a different file (and/or repeated, but with extra indenting) to the log containing the problem.

Describe the solution you'd like
Analyzer should interpret the line at the start of a log indicating rotation