Allow category names with different casing (fixes #3465)

(cherry picked from commit 4bc228880654320fdeec3d337d4dd948c5ab1269)

# Conflicts:
#	app/src/main/java/eu/kanade/tachiyomi/data/database/models/Category.kt

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupManager.kt

@@ -359,7 +359,7 @@ class BackupManager(val context: Context, version: Int = CURRENT_VERSION) {
             for (dbCategory in dbCategories) {
                 // If the category is already in the db, assign the id to the file's category
                 // and do nothing
-                if (category.nameLower == dbCategory.nameLower) {
+                if (category.name == dbCategory.name) {
                     category.id = dbCategory.id
                     found = true
                     break
@@ -387,7 +387,7 @@ class BackupManager(val context: Context, version: Int = CURRENT_VERSION) {
         val mangaCategoriesToUpdate = mutableListOf<MangaCategory>()
         for (backupCategoryStr in categories) {
             for (dbCategory in dbCategories) {
-                if (backupCategoryStr.toLowerCase() == dbCategory.nameLower) {
+                if (backupCategoryStr == dbCategory.name) {
                     mangaCategoriesToUpdate.add(MangaCategory.create(manga, dbCategory))
                     break
                 }

app/src/main/java/eu/kanade/tachiyomi/data/database/models/Category.kt

@@ -16,9 +16,6 @@ interface Category : Serializable {
     var mangaOrder: List<Long>
     // SY <--
 
-    val nameLower: String
-        get() = name.toLowerCase()
-
     companion object {
 
         fun create(name: String): Category = CategoryImpl().apply {

app/src/main/java/eu/kanade/tachiyomi/ui/category/CategoryPresenter.kt

@@ -101,6 +101,6 @@ class CategoryPresenter(
      * Returns true if a category with the given name already exists.
      */
     private fun categoryExists(name: String): Boolean {
-        return categories.any { it.name.equals(name, true) }
+        return categories.any { it.name == name }
     }
 }