This ticket implements an interface to read databases of reflexive polytopes:

• Add databases in PALP format to the polytopes_db.spkg.
• A class PALPreader that can read the palp output and yield it in various Sage representations.
• Finally, this ticket contains a specialized PPL lattice polytope that is fast enough to construct to go through the 500 million 4-d reflexive polytopes and compute integral points.

The updated polytopes spkg is here:
http://boxen.math.washington.edu/home/vbraun/spkg/polytopes_db-20120220.spkg

Apply:

• attachment: trac_12553_ppl_count_points.patch
• attachment: trac_12553_ppl_lattice_polytope.patch
• attachment: trac_12553_palp_database.patch

Depends on #11763
Depends on #11634
Depends on #12544
Depends on #14467

CC: @novoselt @jdemeyer

Component: packages: huge

Keywords: PALP reflexive polytopes

Author: Volker Braun

Reviewer: Dmitrii Pasechnik

Merged: sage-5.10.beta2

Issue created by migration from https://trac.sagemath.org/ticket/12553