Roleback patch to issue #62, no more manual flush control but not an auto-flush xml writer. One flush is issued at the end of xml generation.
A few final added to XmlWriter
Correction for issue #63: Fail to create RrdDb instance from a XML created by RRDatabase instance and a test case for it.

A flush added too.
Small cleaning JrrdTest
fix calendar field handling. (thanks to Ronald Roskens from jrobin)
Small typo in a error message
no inversion of ulock and rlock
a pool with conditionnal variable
Updated plugin versions
Merge branch 'master' into newPoolLocking

* master:
  Updated plugin versions
Improved pool multi-threading, easier to understand code
Improved pool multi-threading, easier to understand code, step 2
Improved pool multi-threading, easier to understand code, reformated code
last (?) lock case removed from the pool
Improved time zone usage
Improved time zone usage, updated TestDemo, not quite sure about it
New KISS pool, even more scalable.
Test failed with new TimeZone settings
Updated javadoc
Removed CR in license file