Bugix search API endpoint; migrate from hnsearch.com to hn.algolia.io

Break fix for search API; resolves issue #64

- Migrated from `hn.search.com` to `hn.algolia.io` URL
- Updated extensive amounts of JSoup/GSon data structures
- Removed newly invalid features (sort by points, etc.)
- Added `ITEM_TYPE_INVALID` for displaying results that would otherwise throw errors