Added a multiplication for free modules.
#8698: German translation of the document "A Tour of Sage"
Proof reading for the German version of "Tour of Sage". Adding the two missing plots. Adding as section on the Sage notebook.
trac #8698 correct one doctest + put images in place
trac #8698 reviewer comments
Merge branch 'public/modules/free_module_mul-5131' of ssh://trac.sagemath.org:22/sage into 5131
trac #5131 typo corrected in the doc of new method _mul_
translate comments into German
Trac #5131: regression in free modules -- who broke my __mul__

If A is a free module and r a ring element then r*A and A*r used to work
fine. But somebody broke them.

In the good ol days:
{{{
wstein@sage:/disk/scratch/mabshoff-sage-releases/sage-0.10.0$ ./sage
[...]
sage: A = ZZ^3
sage: A
 _5 = Ambient free module of rank 3 over the principal ideal domain
Integer Ring
sage: 2*A
 _6 =
Free module of degree 3 and rank 3 over Integer Ring
Echelon basis matrix:
[2 0 0]
[0 2 0]
[0 0 2]
}}}

Now:
{{{
sage: A = ZZ^3
sage: 2*A
Traceback (most recent call last):
...
TypeError: unsupported operand parent(s) for '*': 'Integer Ring' and
'<class 'sage.modules.free_module.FreeModule_ambient_pid'>'
}}}

URL: http://trac.sagemath.org/5131
Reported by: was
Ticket author(s): Travis Scrimshaw
Reviewer(s): Jan Keitel
Trac #8698: German translation of the document "A Tour of Sage"

As the subject says. Because the patch on this ticket is short, I think
this ticket takes much less work to review than #8660. So it's very
likely that the current ticket would be merged first, then #8660.
Someone who knows German needs to look over the attached patch.

See this [http://groups.google.com/group/sage-
support/browse_thread/thread/c14c761ee3dc5203 sage-support] thread for
background information.

URL: http://trac.sagemath.org/8698
Reported by: mvngu
Ticket author(s): Bernhard Bloechl
Reviewer(s): Minh Van Nguyen, André Apitzsch