Cedar-backup3

* 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

* Fix testEncodePath_009() to be aware of "UTF-8" encoding.
* Fix typos in the PostgreSQL extension section of the manual.
* Improve logging when stage action fails (closes: 1854635).
* Fix stage action so it works for local users (closes: 1854634).

* Updated copyright statements now that code changed in year 2008.
* Fix two unit test failures when using Python 2.5 (SF 1861878).
- Add new function testtutil.hexFloatLiteralAllowed()
- Fix splittests.TestByteQuantity.testConstructor_004() for 0xAC
- Fix configtests.TestBlankBehavior.testConstructor_006() for 0xAC

* Improve error reporting for managed client action failures.
* Make sure that managed client failure does not kill entire backup.
* Add appendix "Securing Password-less SSH Connection" to user manual.

* Minor documentation tweaks discovered during 3.0 development.
* Add support for a new managed backup feature.
- Add a new <peers> configuration section (PeersConfig)
- Change peers configuration in <stage> to just override <peers>
- Modify stage process to take peers list from peers section (if available)
- Add new configuration in options and remote peers to support remote shells
- Update user manual to discuss managed backup concept and configuration
- Add executeRemoteCommand() and executeManagedAction() on peer.RemotePeer

* Deal properly with programs that localize their output.
- Create new util.sanitizeEnvironment() function to set $LANG=C
- Call new sanitizeEnvironment() function inside util.executeCommand()
- Change extend/split._splitFile() to be more verbose about problems
- Update Extension Architecture Interface to mandate $LANG=C
- Add split unit tests to catch any locale-related regressions
- Thanks to Lukasz Nowak for initial debugging in split extension