Add support for vfile message notes

Closes GH-26.
Closes GH-28.

Reviewed-by: Christian Murphy <[email protected]>
Reviewed-by: Titus Wormer <[email protected]>

Author: remcohaszing

lib/index.js

@@ -128,6 +128,10 @@ function vfileMessageToDiagnostic(message) {
     }
   }
 
+  if (message.note) {
+    diagnostic.message += '\n' + message.note
+  }
+
   return diagnostic
 }
 

test/index.js

@@ -248,6 +248,11 @@ test('`textDocument/didOpen`, `textDocument/didClose` (and diagnostics)', async
           range: {start: {line: 0, character: 0}, end: {line: 0, character: 0}},
           message: 'nothing',
           severity: 2
+        },
+        {
+          range: {start: {line: 0, character: 0}, end: {line: 0, character: 0}},
+          message: 'note\nThese are some additional notes',
+          severity: 2
         }
       ],
       'should emit diagnostics on `textDocument/didOpen`'

test/lots-of-warnings.js

@@ -30,5 +30,8 @@ export default function lotsOfWarnings() {
     })
     file.message('point', {line: 2, column: 3})
     file.message('nothing')
+    Object.assign(file.message('note'), {
+      note: 'These are some additional notes'
+    })
   }
 }