Cedar-backup3

* Fix cback-span problem when writing store indicators.

* Fix bug when logging strange filenames.

* Add the ability to dereference links when following them.
- Add util.dereferenceLink() function
- Add dereference flag to FilesystemList.addDirContents()
- Add CollectDir.dereference attribute
- Modify collect action to obey CollectDir.dereference
- Update user manual to discuss new attribute

* Updated copyright statement slightly.
* Updated user manual.
- Brought copyright notices up-to-date
- Fixed various URLs that didn't reference SourceForge
* Fixed problem with link_depth (closes: 1930729).
- Can't add links directly, they're implicitly added later by tar
- Changed FilesystemList to use includePath=false for recursive links

* Change suggested execution index for Capacity extension in manual.
* Provide support for application-wide diagnostic reporting.
- Add util.Diagnostics class to encapsulate information
- Log diagnostics when Cedar Backup first starts
- Print diagnostics when running unit tests
- Add a new --diagnostics command-line option
* Clean up filesystem code that deals with file age, and improve unit tests.
- Some platforms apparently cannot set file ages precisely
- Change calculateFileAge() to use floats throughout, which is safer
- Change removeYoungFiles() to explicitly check on whole days
- Put a 1-second fudge factor into unit tests when setting file ages
* Fix some unit test failures discovered on Windows XP.
- Fix utiltests.TestFunctions.testNullDevice_001()
- Fix filesystemtests.TestBackupFileList.testGenerateFitted_004()
- Fix typo in filesystemtests.TestFilesystemList.testRemoveLinks_002()

* Make name attribute optional in RemotePeer constructor.
* Add support for collecting soft links (closes: 1854631).
- Add linkDepth parameter to FilesystemList.addDirContents()
- Add CollectDir.linkDepth attribute
- Modify collect action to obey CollectDir.linkDepth
- Update user manual to discuss new attribute
- Document "link farm" option for collect configuration
* Implement a capacity-checking extension (closes: 1915496).
- Add new extension in CedarBackup2/extend/capacity.py
- Refactor ByteQuantity out of split.py and into config.py
- Add total capacity and utilization to MediaCapacity classes
- Update user manual to discuss new extension