A potential bug (#136)

- fixing the value of the `end` variable - the index of the text end
    - this should match with all the conditions where `end` is used
- discovered while aligning FantasyCoref with its original texts
- Martin checked that the update doesn't violate processing of LitBank, for which the block was originally designed for

Author: michnov

udapi/block/read/addtext.py

@@ -32,7 +32,7 @@ def process_document(self, document):
             self.finished = True
             return
         text = ''.join(self.filehandle.readlines())
-        i, end, was_newpar = 0, len(text), True
+        i, end, was_newpar = 0, len(text)-1, True
         while i <= end and text[i].isspace():
             i += 1