[java] Allow Null<NativeArray> to be optimized to use native accessors
[java/cs] (WIP) - issue #2493
[java] Fixed bad haxe.Template type inferention. Closes #2254
[java] do/while(false) is not dead code. Closes #2271
[java/cs] Enabled reflection access for AccNever. Closes #2272
[java] Explicit call to @:extern non-inline methods will assume there's a @:functionCode that declares it somewhere. Closes #2493