Implements task-23046.

As log files can be compressed very efficiently log descriptor raw bytes contain
the compressed bytes.

Added methods for accessing uncompressed log content, as well as stream based
methods for decompression and compression in class FileType.
Adapted all tests to the changes.

Implements task-25329.

For both the general LogDescriptor and extension WebServerAccessLog.
Include some new tests.

Implements #22990.

And, allow for roughly a years worth of entries in dateMap and requestMap before
re-hashing by setting initial capacity.  Defaults are fine for the small ipMap
and protocolMap.

Also make validation optional for internal web log constructor.
CollecTor uses this for storing freshly sanitized logs,
which don't need to be validated a second time.

Implements task-22983 and is based on the log-descriptor
specification.

Implements part of task-21414.
Adapt IndexNode to supply a revision.

Implement task-23597.  Reflect changes of links in Trac module names
and Metrics' website.

But override the switch from Java 7 to 8 until all metrics libraries
depending on metrics-lib have upgraded to Java 8 first.

The different tests have separate methods for clarity when tests fail.
This is more important than the additional overhead of repeated
iteration over the test-descriptors, which are kept small.

Fixes #22912.

This currently breaks Jenkins build, which is not exactly our fault
but Jenkin's. But this is test code, so it's easier to just adapt.

Also include missing change log entry that was supposed to go into
2.0.0.