Also update the license and switch to GPL v2 like lammps

This is a squashed commit including the following changes:
1) Update mode header
2) Clean up white-space
3) Fix free variable warning
4) Add proper file ending stuff
5) Rename to keep conventional naming scheme
6) Updates to the readme
7) Update to conform to `package-lint` criteria
8) Add license header
9) Add in-file instructions

Some output fields have attributes attached on the same
line. e.g. "ITEM: BOX BOUNDS pp pp pp". This patch replaced all
the strcmpi to strncmpi in order to limit the number of character
compared with LAMPPS outputs.

Signed-off-by: Yossi Eliaz <eliaz123@gmail.com>

When compiling with g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18) an error occurs: 
error.cpp: In member function ‘void Error::generate_error(unsigned int, std::string, std::string)’:
error.cpp:146: error: ‘exit’ was not declared in this scope
The fix is to include the #include <cstdlib> where the exit() function is decleared in the error.cpp file

are provided.

        New directory: tools/doxygen

        New file:      tools/doxygen/Developer.dox.lammps
        New file:      tools/doxygen/Doxyfile.lammps
        New file:      tools/doxygen/doxygen.sh
        New file:      tools/doxygen/README

The Developer.dox.lammps file contains a slightly revised version of the
Developer.pdf file adopted to the LAMMPS "doxygen" documentation.

The Doxyfile.lammps file is a first proposal for a LAMMPS "doxygen"
documentation flavor and can be adjusted to specific requirements.

The "doxygen.sh" shell script generates the LAMMPS "doxygen"
documentation.

Detailed instructions can be found in the README file.

- include the used tricubic functions directly as static functions
- silence compiler warnings
- define f2c.h imported data types directly or use C equivalents
- since the direct LAPACK API was called and not cLAPACK, declare LAPACK interface and depend only on LAPACK
- add proper dependencies
- disable automatic minor version number generation. step version manually.
- comment out optional spglib functionality by default

data2xmovie was removed in e110d696

- put a note into the manual
- reorder contents of the README file
- request for information should be sent to lammps-users
- add list of known missing features

changes for next patch, 2d disc options for spheres, fix external upgrade, bug fixes for fix ave/chunk for density calcs, Aidan doc page citation deconvolution