Add collapse series, add filter by series include sequence and sort, show number of episodes on podcast card

server/objects/mediaTypes/Podcast.js

@@ -57,7 +57,7 @@ class Podcast {
       metadata: this.metadata.toJSON(),
       coverPath: this.coverPath,
       tags: [...this.tags],
-      episodes: this.episodes.map(e => e.toJSON()),
+      numEpisodes: this.episodes.length,
       autoDownloadEpisodes: this.autoDownloadEpisodes,
       lastEpisodeCheck: this.lastEpisodeCheck,
       size: this.size

server/objects/metadata/BookMetadata.js

@@ -151,6 +151,12 @@ class BookMetadata {
   hasNarrator(narratorName) {
     return this.narrators.includes(narratorName)
   }
+  getSeries(seriesId) {
+    return this.series.find(se => se.id == seriesId)
+  }
+  getFirstSeries() {
+    return this.series.length ? this.series[0] : null
+  }
   getSeriesSequence(seriesId) {
     var series = this.series.find(se => se.id == seriesId)
     if (!series) return null