JDK8, lint fixing (#2888)

* Use Kotlin JDK8

* Satisfy a ton of lints

* Run res/layout files (and manifest) through reformatter

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryCategoryView.kt

@@ -229,13 +229,13 @@ class LibraryCategoryView @JvmOverloads constructor(context: Context, attrs: Att
     override fun onItemClick(view: View?, position: Int): Boolean {
         // If the action mode is created and the position is valid, toggle the selection.
         val item = adapter.getItem(position) ?: return false
-        if (adapter.mode == SelectableAdapter.Mode.MULTI) {
+        return if (adapter.mode == SelectableAdapter.Mode.MULTI) {
             lastClickPosition = position
             toggleSelection(position)
-            return true
+            true
         } else {
             openManga(item.manga)
-            return false
+            false
         }
     }
 

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryPresenter.kt

@@ -303,7 +303,7 @@ class LibraryPresenter(
         if (mangas.isEmpty()) return emptyList()
         return mangas.toSet()
                 .map { db.getCategoriesForManga(it).executeAsBlocking() }
-                .reduce { set1: Iterable<Category>, set2 -> set1.intersect(set2) }
+                .reduce { set1: Iterable<Category>, set2 -> set1.intersect(set2).toMutableList() }
     }
 
     /**