Realign virtual tabs when applying fix

Fix an off-by-one error, in the case that is commented `should never happen`.
It happens when the end of a range is the at the end of a line.
In that case we should update the real column count (probably just by +1)
instead of returning it.

I modified makeNonVirtual to use a helper, realign, that works on
Ranged. That way we can share the code to realign a PositionedComment
and also a Replacement.

Fixes #1420

src/ShellCheck/Fixer.hs

@@ -16,20 +16,38 @@ class Ranged a where
             yEnd = end y
             xStart = start x
             xEnd = end x
+    -- Set a new start and end position on a Ranged
+    setRange :: (Position, Position) -> a -> a
+
+instance Ranged PositionedComment where
+    start = pcStartPos
+    end = pcEndPos
+    setRange (s, e) pc = pc {
+        pcStartPos = s,
+        pcEndPos = e
+    }
 
 instance Ranged Replacement where
     start = repStartPos
     end   = repEndPos
+    setRange (s, e) r = r {
+        repStartPos = s,
+        repEndPos = e
+    }
 
 instance Ranged a => Ranged [a] where
     start [] = newPosition
     start xs = (minimum . map start) xs
     end []   = newPosition
     end xs   = (maximum . map end) xs
+    setRange (s, e) rs = map (setRange (s, e)) rs
 
 instance Ranged Fix where
     start = start . fixReplacements
     end   = end . fixReplacements
+    setRange (s, e) f = f {
+        fixReplacements = setRange (s, e) (fixReplacements f)
+    }
 
 -- The Monoid instance for Fix merges replacements that do not overlap.
 instance Monoid Fix where