fix(gulp): switch xml lint library

see eXist-db#431

Gulpfile.js

@@ -43,9 +43,12 @@ var paths = {
     output: 'src/main/xar-resources/resources/'
   },
   fonts: {
-    output: 'src/main/xar-resources/resources/fonts/',
+    output: 'src/main/xar-resources/resources/fonts/'
   },
-  listings: 'src/main/xar-resources/data/*/listings/*.xml'
+  xml: {
+    listings: 'src/main/xar-resources/data/*/listings/*.xml',
+    articles: 'src/main/xar-resources/data/*/*.xml'
+  }
 }
 
 /**
@@ -86,7 +89,7 @@ var lazypipe = require('lazypipe')
 var rename = require('gulp-rename')
 var header = require('gulp-header')
 var pkg = require('./package.json')
-var prettyData = require('gulp-pretty-data')
+var muxml = require('gulp-muxml')
 
 
 // Scripts
@@ -196,18 +199,19 @@ var lintScripts = function(done) {
   done()
 }
 
-// minify and lint xml
+// pretty print all xml listings
+// articles not yet decided
 var prettyXml = function(done) {
-  src(paths.listings, { base: "./" })
-  .pipe(prettyData({
-      type: 'minify',
-      preserveComments: true
-    }))
-    // … then pretty print xml
-    .pipe(prettyData({
-        type: 'prettify',
-        preserveComments: true
-      }))
+  src(paths.xml.listings, { base: "./" })
+  .pipe(muxml({
+    stripComments: false,
+    stripCdata: false,
+    stripInstruction: false,
+    saxOptions: {
+      trim: true,
+      normalize: true
+    }
+  }))
     .pipe(dest("./"))
     // Signal completion
     done()

package.json

@@ -39,8 +39,8 @@
     "gulp-cssnano": "^2.1.3",
     "gulp-flatmap": "^1.0.2",
     "gulp-header": "^2.0.9",
+    "gulp-muxml": "^2.0.0",
     "gulp-optimize-js": "^1.1.0",
-    "gulp-pretty-data": "^0.1.2",
     "gulp-rename": "^2.0.0",
     "gulp-sass": "^4.0.2",
     "gulp-sourcemaps": "^2.6.5",