support xib and storyboard obfuscation with command line option

[ptwoms]

I added this because my projects use storyboards and xibs and it takes time to update xml files manually after source obfuscation.
IB XML obfuscation is added as an option (--include-ibxmls) and is not enabled by default.

[rockbruno]

I actually supported this feature at one point, but I removed it because there were far too many reports of things not being obfuscated correctly (for example, obfuscating a method configured as an outlet) because the storyboards have a billion different ways of storing this information. I considered it impossible to maintain properly, are you confident that this works for all cases?

[ptwoms]

It basically looks for any xml tags with customClass attribute for custom class (and customModule for ignore modules) as long as the class name is in the obfuscated dictionary. And selector with parent tag connections (destination -> customModule for ignore modules) for IBAction. It is working fine on the projects I am working on.

I haven't come across other patterns yet. If they can provide the sample IB file I can look into it. That's why I put this option as experimental.