Definition tweaks: #64, #65, #66, #67

* #64: Check for "exception" definitions -- i.e. do not let an exception to a definition overwrite the initial definition
* #65: Add interpretation to the scope of a definition. Now a definition scoped to 2322-32 will also apply in 2322-Interpretations-32
* #66: Catch a few more definitions. Instead of just checking for "definitions" within the text, also look for the phrase 'the term .* means'
* #67: Don't add a term as a defined term *while you are defining it*.