IR: Introduce Translators, an abstraction for IR translation

Translators exposes method to convert Miasm IR to others languages
IR/Translator: Add a translator for IR -> C, comming from ir/ir2C.py
IR/Translator: Add a translator for IR -> Python
IR/Translator: Exposes Translator from miasm2.ir.translators
ir2C: Refactor ir2C to extract TranslatorC part
Test: Update API of ir2C test
Example: Add a new example using C & Python translation
Merge pull request #23 from commial/refactor-irtranslators

Introduce IR Translators