Updated EVAddVariable.R function

[yangyangMarine]

Enabled adding additional arguments to assign parent variable to the new added one. This could be useful when using some algorithms, for example, single target detection and mask which need two or more operator variables. Soon will also add a look up table for enum argument input.

[raymondben]

On review, we've decided that this method of adding additional arguments is beyond the scope of the package, sorry. Our recommendation is that users create a basic object via EVAddVariable() and - if necessary- modify that object themselves after creation.

[yangyangMarine]

On review, we've decided that this method of adding additional arguments is beyond the scope of the package, sorry. Our recommendation is that users create a basic object via EVAddVariable() and - if necessary- modify that object themselves after creation.

Thanks for reviewing on this Ben! That makes sense. I will probably just keep it on my private repo since oringially I was gonna use this to accelerate building an Echoview workflow.