Made tachyon use the standard verbosity setting as default.

If no optional verbosity setting argument is provided to Tachyon.show
or Tachyon.save, then they use the global verbosity level set by
sage.misc/misc.set_verbose.
Introduced doctests to illustrate effects of changing global verbosity.

Created three different examples that illustrate how Tachyon.show
uses Sage's global verbosity setting if none is provided.
Remove workaround for old Pyrex
Merge with 6.4.beta2

Conflicts:
	src/sage/plot/plot3d/tachyon.py
Return FFELT in GF(q) -> PARI conversion
Update buckygen package for the sage-git directory layout
Trac #16915: Remove workaround for old Pyrex in element_givaro.pyx

This is just a small thing I noticed while reading this code. I am also
adding a few doctests to check for #16807 for Givaro finite fields.

URL: http://trac.sagemath.org/16915
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): Volker Braun
Merge branch 'ticket/16930' into ticket/16944
Remove impl="pari_ffelt" options for finite fields
Trac #16228: make tachyon respect standard verbosity settings

`Tachyon.save` and `Tachyon.show` have their own arguments for verbose
output and do not pay attention to the verbosity levels set by
`sage.misc.misc.set_verbose`.  This makes for inconsistent and confusing
interface.

Instead of checking the value of an optional argument, these methods
should check sage's verbosity setting.  This is done implicitly when
messages are printed with `sage.misc.misc.verbose`.  An explanation of
this change should be added to the documentation.

URL: http://trac.sagemath.org/16228
Reported by: niles
Ticket author(s): Paul Graham
Reviewer(s): Dima Pasechnik
Trac #16944: GF(q) -> PARI: always return FFELT

The finite field implementations `givaro` and `ntl` should return a
`t_FFELT` when a finite field element is converted to PARI.

URL: http://trac.sagemath.org/16944
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): Volker Braun
Trac #16945: Switch buckygen package to sage-git directory layout

The package still uses the old spkg format.

URL: http://trac.sagemath.org/16945
Reported by: nvcleemp
Ticket author(s): Nico Van Cleemput
Reviewer(s): Volker Braun