[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

docs/supportedsites.md

@@ -229,6 +229,12 @@ Consider all listed sites to potentially be NSFW.
     <td>Albums, Search Results, User Profiles</td>
     <td></td>
 </tr>
+<tr>
+    <td>Everia</td>
+    <td>https://everia.club</td>
+    <td>Categories, Dates, Posts, Search Results, Tag Searches</td>
+    <td></td>
+</tr>
 <tr>
     <td>ExHentai</td>
     <td>https://exhentai.org/</td>