* The log history of a test is stored as a whole for the lifetime of the test.
* Matching of the log history against log patterns is done correctly now
(previously, a pattern like "AAB" on an input like "AAAB" wouldn't have
triggered).
* Use memcmp, memcpy, memmove instead of the former character-wise operations.
* Sanitizing of log input and log patterns now works more generic through the
new Filter class for all replacements/removals.
* Sanitizing is done as soon as a string is available and remains for the
lifetime of the test.
* Sanitizing doesn't interfer with the matching algorithm.
* Decomposing into small clearly named functions.
Ref #3555