Configurable match expansion

[margaretha]

During the implementation of #144, we found an existing behavior relevant for the Corola instance, that match shouldn't be expanded (to sentences) when there is no sentence boundary, e.g. there is no sentence annotations in the data. Before #144, match expansion was restricted to match size only.

This behavior changes because match expansion now considers match context size. To keep the previous behavior, we can make match expansion configurable using krill properties by setting a property as follows.

krill.match.expansion.includeContextSize = true

where the default value is false.