corrected faulty getValueAsCode() method in SaveFolderStringType
Two small changes in ArrayBaseType:
1. call to dispose() of each TypeRepresentation in the array
    — when array's dispose() is called,
    — when an entry of the array is removed (via the »—« button);
2. removed one superfluous call to setViewValue().
Another small change in ArrayBaseType:
Call to the sub-objects’ addedToMethodRepresentation() in addedToMethodRepresentation removed.
Merge pull request #23 from cpoliwoda/master

duplicate plugin identifiers error message improved #22
Merge pull request #25 from cpoliwoda/master

fixed: VRL-Tutorial-Plugin dublicate installation, wrong error message
Merge pull request #17 from bsumirak/master

correction for SaveFolderStringType, ArrayBaseType
resolving issue  circular plugin dependencies did not show which plugins are involved #27 on https://github.com/miho/VRL/issues/27