Properly fix JavaDoc linting issues

Fixes our own, and upstream's, issues with the stricter Java 8 JavaDoc
linter.

Also removes the destroystokyo-release maven repository. I'm not sure
why I added it originally, but it's unnecessary now.

Spigot-API-Patches/0023-Use-ASM-for-event-executors.patch

@@ -1,4 +1,4 @@
-From 31a91b94783da85083becaa48afbad20fc8019bb Mon Sep 17 00:00:00 2001
+From 2ba17bea4632f1947234d462d0e7bc597450f0fe Mon Sep 17 00:00:00 2001
 From: Techcable <Techcable@outlook.com>
 Date: Thu, 3 Mar 2016 13:20:33 -0700
 Subject: [PATCH] Use ASM for event executors.
@@ -6,10 +6,10 @@ Subject: [PATCH] Use ASM for event executors.
 Uses method handles for private or static methods.
 
 diff --git a/pom.xml b/pom.xml
-index 5336fe55..a9009636 100644
+index 04168f66..862910e0 100644
 --- a/pom.xml
 +++ b/pom.xml
-@@ -128,6 +128,12 @@
+@@ -127,6 +127,12 @@
              <version>1.3</version>
              <scope>test</scope>
          </dependency>