Extracted ValueHolder from DataField.
Added snakeyaml to dependencies
Rewrote YamlNode
More work on ValueHolders - added getters with default
More work on YamlNode:
* treat SnakeYaml's output as read-only
* added more children-adding methods
* added node-counting methods
Random fixes and javadocs.
Overhauled YamlManager to use SnakeYaml and the new YamlNode
Added YamlCombiner
Added getFinalNodeCount() to YamlManager
Random fixes and javadocs.
Fixed one NPE in YamlNode
Fixed some bugs in ValueHolderBase and made some fields private.
Fixed some bugs in YamlNode, improved Settings
Fixes in SimpleYamlManager, YamlManager and YamlCombiner.
* not loading the yaml in manager's constructor anymore
* YamlCombiner.setLoggingManager() now sets the logger for all the
sub-YamlManagers
* fixed byte array to number conversions
* other minor fixes
Added Mockito dependency. Added new unit tests and improved existing.
Added missing license headers.
Added getFinalNodeList() and old deprecated getNodes()
Removed some trailing whitespace from pom.xml
Merge pull request #30 from Wolf480pl/snake

New Yaml managers, based on SnakeYaml
Made warning methods of LoggingManager public.