Portuguese translation of "Tutorial"

[goliveira]

Portuguese translation of "Tutorial".

It depends on #12502 in a minor way. (In fact, it depends only on the addition of 'pt' in build_options.py)

There is a first revision to the original translation to be applied on top of it. This revision originated from a discussion at sage-devel:

​https://groups.google.com/d/topic/sage-devel/2fjtcJTTNr8/discussion

---

Apply trac_12502_pt_translation_of_a_tour_of_sage_rebase1.patch​

Then apply trac_12822_pt_translation_of_tutorial.patch​

Then apply trac_12822_pt_translation_of_tutorial_rev1.patch​

[pcpa]

In doc/pt/tutorial/programming.rst

Removed untranslated "preparsing", should have used "pré-processamento".

I know I commented about "macro" not having a proper translation in pt_BR, but it is already so commonly used, that it should be better to use it instead of "função" (english function).

Remaining looks good, but I still make considerations about conversion and coercion, that by themselves are also confusing in english, and pt_BR makes things worse by having several translations for coercion, most of which are about forced to do something, slavering, etc :-)

It is also funny that "coercion" accordingly to sage documentation stand for "implicit conversion", but common lisp has the function "coerce" that is used for "explicit conversion".

[r.gaia.cs]

I have rebase the #12502.

IMHO, it best to translate the comments of the codes, e.g., in the place of

    sage: 2**3    #  ** means exponent

should be use

    sage: 2**3    #  ** indica potenciação