Logging: issue INFO, not WARNING, if LaTeX .sty file can't be read.

Normally this is not a situation requiring a fix from the user,
so a warning is inappropriate.

changelog

@@ -46,6 +46,10 @@ pandoc (2.0.1.1)
 
   * Improve `pandoc-template-mode.el` (Vaclav Haisman).
 
+  * Issue INFO, not WARNING, when a .sty file cannot be
+    read in LaTeX reader.  It is normally not an issue requiring
+    a fix from the user if .sty files are not found.
+
   * INSTALL.md: MacOS instructions needed xar -f (adam234).
 
   * MANUAL.txt:

src/Text/Pandoc/Logging.hs

@@ -45,6 +45,7 @@ import Data.Aeson.Encode.Pretty (Config (..), defConfig, encodePretty',
                                  keyOrder)
 import qualified Data.ByteString.Lazy as BL
 import Data.Data (Data, toConstr)
+import Data.List (isSuffixOf)
 import qualified Data.Text as Text
 import Data.Typeable (Typeable)
 import GHC.Generics (Generic)
@@ -315,7 +316,9 @@ messageVerbosity msg =
        ReferenceNotFound{}          -> WARNING
        CircularReference{}          -> WARNING
        UndefinedToggle{}            -> WARNING
-       CouldNotLoadIncludeFile{}    -> WARNING
+       CouldNotLoadIncludeFile f _
+        | ".sty" `isSuffixOf` f     -> INFO
+        | otherwise                 -> WARNING
        MacroAlreadyDefined{}        -> WARNING
        ParsingUnescaped{}           -> INFO
        InlineNotRendered{}          -> INFO