#92 Allow discourse-coder elements to nest over identical words

[Jonathan Kilgour]

Currently you can configure the discourse coder tool to allow nesting of elements (named-entities) by setting the nenesting config option. However this does not allow nesting when the selected set of words is identical to that of an existing element. You can however allow a single element to point into the type hierarchy multiple times by setting the nemultipointers config option.

However, there are cases where one would like named entities over the same set of words to actually nest. Invent a suitable config file setting for this and implement it...