Add Digit Obfuscation to Mangler

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Digit obfuscation or expansion could improve certain Mutator's complexity greatly. Functionality needs to be added to the Mangler class to obfuscate integers into complex arithmetic expressions, using arbitrary number bases. This also needs to take the user's size preference into account, obfuscating the input digits a little or a lot depending on the sizePref value.

• Add random base mangling
• Add arithmetic expansions ie 14 -> (7*-(-8+6))
• Add more mangling inside of arithmetic expansions