[everia.club] Add support

- Unescape title and URL
- Add tags and categories metadata
    Lookup tag id with API instead of downloading tag page
- Add category extractor
- Add tests
- Rename EveriaExtractor to EveriaPostExtractor
- Fix EveriaPostExtractor example
- Lookup tags/categories by post id
- Add date extractor
- Remove leftover pages parameter
- Add error handling for invalid dates.
- Add filename numbering
    Parse date
- Rename extract() to images()
- Remove html import
- Fix search/date URLs with page number
- Fix tag/category search
- Fix post extractor
- Fix tag, category extractors
- Fix search extractor
- Only load first page once
- Fix date extractor
- Fix tests
- Clean up search extractor

gallery_dl/extractor/__init__.py

@@ -47,6 +47,7 @@ modules = [
     "dynastyscans",
     "e621",
     "erome",
+    "everia",
     "exhentai",
     "fanbox",
     "fanleaks",