Removed redundant compiler configuration.

The same configuration is in the master pom.
(Verified by diffing the effective POM as presented by Eclipse m2e.)
Set Java version from property instead of by plugin configuration.

This makes it somewhat easier to override the Java version from
child POMs.
Also, it does not nail down the maven-compiler-plugin version
anymore. Sure enough, this bumped the version from 2.3.1 to 2.3.2
(2.3.2 fixes http://jira.codehaus.org/browse/MCOMPILER-109).
Merge pull request #79 from toolforger/maven-cleanup

Maven cleanup
Take current threads contextClassLoader for resource loading, which is more flexible
Improved drag and drop

Added possibility to manually change the droppable that is parent to a draggable
Merge remote-tracking branch 'GitHub-void/1.4' into 1.4
Merge pull request #80 from mkaring/1.4

Improved drag and drop
Improved drag and drop

Added support to properly enable and disable the draggable without corrupting the state of the GUI
Merge pull request #86 from mkaring/1.4

Improved drag and drop
Made Element.findElementByName() deprecated, offer Element.findElementById() instead with same functionality
Merge pull request #87 from floyd1982/1.4

1.4
update jogl jars to the maven central artifacts
Merge branch '1.4' of git@github.com:void256/nifty-gui.git into 1.4
Added getter methods for padding and margin attributes in Element
Bugfix: Element.findElementById() didn't use the to find element id passed as parameter, but local field which causes every find to return 'this'
Renamed method Screen.findElementByName() to findElementById() according to Element.findElementById(); old method is still available but @Deprecated
Merge pull request #89 from floyd1982/1.4

1.4 Pull request: bugfix, getters for padding and margin fixes #85
Added map to Element for custom user data, for example game entity objects
Improved Element's userData feature: getter is now a generic method; userData map will be only created if used first time
Merge pull request #90 from floyd1982/1.4

Added map to Element for custom user data