Range: The end of the range should point at the last line of the range

To preserve compatibility with Vim, the end of the range should point
at the last line of the range, not at the first line below.

The inconsistency can be demostrated by running (both in Vim and Neovim):

:python import vim; print vim.current.range.start, vim.current.range.end

either with visual range selected or without it.

neovim/api/buffer.py

@@ -166,10 +166,10 @@ class Range(object):
     def __init__(self, buffer, start, end):
         self._buffer = buffer
         self.start = start - 1
-        self.end = end
+        self.end = end - 1
 
     def __len__(self):
-        return self.end - self.start
+        return self.end - self.start + 1
 
     def __getitem__(self, idx):
         if not isinstance(idx, slice):
@@ -179,7 +179,7 @@ def __getitem__(self, idx):
         if start is None:
             start = self.start
         if end is None:
-            end = self.end
+            end = self.end + 1
         return self._buffer[start:end]
 
     def __setitem__(self, idx, lines):
@@ -191,26 +191,26 @@ def __setitem__(self, idx, lines):
         if start is None:
             start = self.start
         if end is None:
-            end = self.end
+            end = self.end + 1
         self._buffer[start:end] = lines
 
     def __iter__(self):
-        for i in range(self.start, self.end):
+        for i in range(self.start, self.end + 1):
             yield self._buffer[i]
 
     def append(self, lines, i=None):
         i = self._normalize_index(i)
         if i is None:
-            i = self.end
+            i = self.end + 1
         self._buffer.append(lines, i)
 
     def _normalize_index(self, index):
         if index is None:
             return None
         if index < 0:
-            index = self.end - 1
+            index = self.end
         else:
             index += self.start
-            if index >= self.end:
-                index = self.end - 1
+            if index > self.end:
+                index = self.end
         return index