English translation of the codestyle

// cc @lemmy-, @tarmolov, @mdevils, @alt-j 
Please, invite any other interested party you can think of.
I used "should" along all the file. I think the "must" rules sound too harsh for codestyle document. Breaking the code style won't break your application, so it shouldn't be that restrictive.
From [RFC 2119](http://www.ietf.org/rfc/rfc2119.txt):
```
1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
   definition is an absolute requirement of the specification.

...
3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.
```
Note the part which says `may exist valid reasons in particular circumstances to ignore a particular item`. I think that the code style is 'guide-like' document, that helps you write better code, but shouldn't restrain you from using a development paradigm even if it is well argument in a particular case, but isn't _allowed_ by the code style.