Fixes a regression in 3.4.0 involving elfeed-search-last-entry and elfeed-search-first-entry.

• New search filter: ~ excludes matching feeds
• Support fetching feeds via file://
• Support fetching feeds via the Gopher protocol
• "End of entries" no longer appears in elfeed-search
• Support bookmarks in entries
• New customizations: elfeed-show-entry-switch, elfeed-show-entry-delete
• More extensive information from elfeed-curl-get-capabilities
• New elfeed-show command: elfeed-kill-link-url-at-point (c)
• Various other minor behavior improvements