Add amos sources

Add double precision amos (http://netlib.org/amos/) sources. The
netlib distribution is insufficient to compile amos. Amos uses
routines such as zabs() and some querying routines such as
d1mach(). The former are taken from SciPy's distribution of amos, the
latter (in a Fortran 90 version using modern constructs such as
tiny()) are taken from a conference proceedings webpage to a
presentation by Bo Einarsson (http://www.nsc.liu.se/~boein/ifip/
kyoto/workshop-info/proceedings/einarsson/einarsson.html). All of
those routines are in principle also part of Slatec.
Add amos interface, also build amos

Interface definitions for the amos routines are added as part of a
module. Also, CMake now also compiles the amos sources. Until further
changes, warnings about implicit interfaces are switched off for all
source files.
Add zbiry() warpper to amos module
Add modern interfaces to the amos routines in special module

The Bessel functions J, Y, the Hankel functions H_1 and H_2, as well as
the modified Bessel functions I and K are added. Furthermore, the
Airy functions Ai and Bi and the respective derivatives are added.
Add unit tests for the amos wrapper
Add error handling for amos routines
Fix Airy function interface
Implement Bessel functions of negative order

NIST Handbook formulas are used.
Complete Bessel&Airy tests

Negative orders are now tested, too. The precision problem has been
fixed by correct array declarations.
Add forgotten CMakeLists.txt for AMOS (oops)
Merge pull request #15 from aeberspaecher/amos

Add AMOS sources and convenience wrappers