L10N Utility

- Combined three l10n utiity scripts into one, which can now do the following:
  - Automatically locate all the localized string files.
  - Look for missing strings in the localized string files.
  - Point out strings that are not used in the code.
  - Count strings.
  - Warn when strings are unchanged across languages.
  - Exit with a status code, so it can be used in unit tests.
- Thanks to Wim Schuermann and Fidel Mato for providing code and ideas.
Merge branch '2.3.0' of tasktools.org:task into 2.3.0
Translated date-related strings into French.
L10N translated new (in 2.3.0) es-ES.h STRING_s

 - Translated 17 strings, mostly STRING_CMD_SYNC_*
 - Also new strings from tasksh, usage message included.
Disallowing tasksh to start in interactive mode (not in batch mode) if no ~/.taskrc exists
Italian translation.
Fixed some few inconsistencies in IT translation strings (removed old strings).
Documentation

- Added it-IT translation details.
Enhancement

- The 'due' urgency component is now calculated at a higher resolution.
Code Cleanup

- Cmake was not updating HAVE_ST_BIRTHTIME.
- NIBBLER_FEATURE_DATE was not properly applied everywhere.
- FEATURE_COLOR was not properly set.
- Some source files failed to include cmake.h, and therefore were not properly
- Removed inefficient use of std::string::substr for guaranteed single character
  strings.
- Integrated Directory::cd.
- Integrated File::ctime, ::btime.
- Integrated Path::operator+.
- Integrated Nibbler::getDigit{2,4,6}.
- Integrated HighResTimer.
  enabling/disabling code.
- All Path objects now expanded internally to absolute form.
- Modified unit tests to accomodate absolute paths.
- Merged new nibbler.t.cpp tests.
- Made various methods const.
- Includes removed from some files, added to others.
Added ability for UDAs to have a default value.
Feature #1256 Follow-up

- Extended unit tests to cover 'add' failures.
- Removed whitespace at EOL.
- Updated ChangeLog, AUTHORS, NEWS.
- Updated taskrc.5.in.
- Updated CmdShow to allow new config settings.
Sync

- When taskwarrior is built without GnuTLS, there will be a message to that
  effect.
- Stubbed the TLSClient calling code.  The current Socket code will become
  obsolete soon.
Sync

- Added task server details to the 'diagnostics' command output.
- Added new configuration variables to the 'show' command.
- rc.taskd.server specifies host:port of the task server.
- rc.taskd.credentials specifies user credentials for the task server.
- rc.taskd.certificate specifies the task server certificate.
- rc.debug.tls shows TLS log information, for debugging.
Documentation

- Added missing dateformat components 'j' and 'J' to the man page.
Sync

- Implemented sync over TLS.
- Obsoleted the Socket code, replacing it with TLSClient, TLSServer.
- Added task server details to the 'diagnostics' command output.
- 'rc.debug.tls' controls the GnuTLS log level.
- Removed redundant cmake diagnostics.
Documentation

- Documented the new configuration settings for task server communication.
Build Errors

- Added missing includes.
Build Error

- Missing include.
Build Error

- More missing/wrong includes.