feature(fabric): added fabric support (#491)

* Initial work towards Fabric compat. This does not compile yet

* Further updates - should compile but Gradle is being weird.

* Remove useless buildscript extras

* Added mixins to buildscript classpath to fix Loom crash

* Make it compile

* Got it building and added interaction

* Fixed review comments

* Use ServerPlayerEntity for FakePlayer

* Use method references for nicer names

* Fixed remaining comments and added networking for CUI

* Output as dist.jar

* Added mixins for left click air

* Use regex for cleanliness

settings.gradle

@@ -2,7 +2,7 @@ rootProject.name = 'worldedit'
 
 include 'worldedit-libs'
 
-['bukkit', 'core', 'forge', 'sponge'].forEach {
+['bukkit', 'core', 'forge', 'sponge', 'fabric'].forEach {
     include "worldedit-libs:$it"
     include "worldedit-$it"
 }