Support emitting a correct end column on SC2086

This does the necessary work to emit end columns on AST analyses. SC2086
is made to emit a correct end column as an illustrative example.

For example:
```
$ shellcheck -s bash -f json /dev/stdin <<< 'echo $1'
[{"file":"/dev/stdin","line":1,"endLine":1,"column":6,"endColumn":8,"level":"info","code":2086,"message":"Double quote to prevent globbing and word splitting."}]
```

This change deprecates the parser's getNextId and getNextIdAt, replacing
it with a new withNextId function. This function has the type signature:

withNextId :: Monad m => ParsecT s UserState (SCBase m) (Id -> b) -> ParsecT s UserState (SCBase m) b

Specifically, it should be used to wrap read* functions and will pass in
a newly generated Id which should be used to represent that node.
Sub-parsers will need their own call to withNextId in order to get a
unique Id.

In doing this, withNextId can now track both the entry and exit position
of every read* parser which uses it, enabling the tracking of end
columns throughout the application.

src/ShellCheck/Checker.hs

@@ -29,6 +29,7 @@ import Data.Functor
 import Data.List
 import Data.Maybe
 import Data.Ord
+import Control.Applicative
 import Control.Monad.Identity
 import qualified Data.Map as Map
 import qualified System.IO
@@ -37,11 +38,14 @@ import Control.Monad
 
 import Test.QuickCheck.All
 
-tokenToPosition map (TokenComment id c) = fromMaybe fail $ do
-    position <- Map.lookup id map
-    return $ PositionedComment position position c
+tokenToPosition startMap endMap (TokenComment id c) = fromMaybe fail $ do
+    position <- maybePosition
+    endPosition <- maybeEndPosition <|> maybePosition
+    return $ PositionedComment position endPosition c
   where
     fail = error "Internal shellcheck error: id doesn't exist. Please report!"
+    maybeEndPosition = Map.lookup id endMap
+    maybePosition = Map.lookup id startMap
 
 checkScript :: Monad m => SystemInterface m -> CheckSpec -> m CheckResult
 checkScript sys spec = do
@@ -62,7 +66,7 @@ checkScript sys spec = do
                 fromMaybe [] $
                     (arComments . analyzeScript . analysisSpec)
                         <$> prRoot result
-        let translator = tokenToPosition (prTokenPositions result)
+        let translator = tokenToPosition (prTokenPositions result) (prTokenEndPositions result)
         return . nub . sortMessages . filter shouldInclude $
             (parseMessages ++ map translator analysisMessages)