[Breaking Change] Rename init and make it not use the super constructor arguments

[NotHyper-474]

Resolves #241

HScriptedClass.init is pretty odd because it's used throughout FNF as the equivalent of new for script classes, but it accepts the super class's constructor arguments as its own, and then initializes an instance of the script class using those arguments, however a script class is actually independent from the super class in this regard and can have any arguments it wants, which may not be the same the super class has. When scripts use it, it causes issues in some targets, where some of the arguments either get converted incorrectly, become null or, on HashLink, throws an error about the incompatible type.

One instance of that in FNF is phillyTrain.hxc, which instantiates an instance of BuildingEffectShader with ScriptedFlxRuntimeShader.init('BuildingEffectShader', 1.0), which calls an init of arguments (Null<String>, Null<String>, Null<String>), it works fine on C++ since there is no type-checking, but on HL it throws an error about being unable to cast a float to a string. This is not a mistake on the script's end, since it does accept a float as its argument.

So I've made it use haxe.Rest for the arguments, however since it doesn't work well with Reflect I had to add some backwards compatibility handling for scripts using it.

The registries and other parts of Haxe code that call init seem to work well with these changes somehow, but I recommend caution regarding any breaking changes this could introduce.

[EliteMasterEric]

Aside from the change I linked, since you're making a potentially breaking change here and adding backwards compatibility for it anyway, it would be nice to implement #241 and rename init to scriptInit for consistency with the other generated methods.

[NotHyper-474]

All done, though now that the function has received a new name it surely is a breaking change for existing Haxe code that used init now.