[lofter] update

- add tests
- update docs/supportedsites
- provide 'date' metadata
- simplify/restructure some code

scripts/supportedsites.py

@@ -86,6 +86,7 @@ CATEGORY_MAP = {
     "kemonoparty"    : "Kemono",
     "koharu"         : "SchaleNetwork",
     "livedoor"       : "livedoor Blog",
+    "lofter"         : "LOFTER",
     "ohpolly"        : "Oh Polly",
     "omgmiamiswimwear": "Omg Miami Swimwear",
     "mangadex"       : "MangaDex",
@@ -265,6 +266,9 @@ SUBCATEGORY_MAP = {
     "lensdump": {
         "albums": "",
     },
+    "lofter": {
+        "blog-posts": "Blog Posts",
+    },
     "mangadex": {
         "feed" : "Followed Feed",
     },