Undeprecate SiteLink methods in Item (#734)

They where deprecated years ago and never removed, presumably cause
there is no clear motivation to do so.

IIRC I deprecated this stuff, but at present I no longer think this
makes things better.

Author: JeroenDeDauw

src/Entity/Item.php

@@ -204,7 +204,6 @@ public function setSiteLinkList( SiteLinkList $siteLinks ) {
 	 * If there already is a site link with the site id of the provided site link,
 	 * then that one will be overridden by the provided one.
 	 *
-	 * @deprecated since 0.8, use getSiteLinkList()->addSiteLink() instead.
 	 * @since 0.6
 	 *
 	 * @param SiteLink $siteLink
@@ -220,7 +219,6 @@ public function addSiteLink( SiteLink $siteLink ) {
 	/**
 	 * Removes the sitelink with specified site ID if the Item has such a sitelink.
 	 *
-	 * @deprecated since 0.8, use getSiteLinkList()->removeLinkWithSiteId() instead.
 	 * @since 0.1
 	 *
 	 * @param string $siteId the target site's id
@@ -230,7 +228,6 @@ public function removeSiteLink( $siteId ) {
 	}
 
 	/**
-	 * @deprecated since 0.8, use getSiteLinkList()->getBySiteId() instead.
 	 * @since 0.6
 	 *
 	 * @param string $siteId
@@ -243,7 +240,6 @@ public function getSiteLink( $siteId ) {
 	}
 
 	/**
-	 * @deprecated since 0.8, use getSiteLinkList()->hasLinkWithSiteId() instead.
 	 * @since 0.4
 	 *
 	 * @param string $siteId