protection from huge triangulation buffer

Stored pyramids skip the triangulation of the pyramids if the triangulation buffer is already twice the limit.
Renamed parallel_in_pyramid to multithreaded_pyramid.
New matrix function kernel()

Computes a ZZ-basis of the solutions of A*x=0, the basis is formed
by the ROWS of the returned matrix.
restructuring of cone.cpp

single/multiple input destinction removed, instead generators/constraints
Merge branch 'master' into excluded_faces

Resolved conflicts:
	libnormaliz/cone.cpp
	libnormaliz/full_cone.cpp
NmzIntegrate update by W.Bruns

various improvements
checking file time stamps and update normaliz output if neccessary
Normaliz update by W.Bruns

inhomogeneous cones
dual mode: general improvements, special deg1 mode
fix for cone_property

the string matching was not updated, causing FatalErrors
Update to use recent CoCoALib version
made the input map to cone const ref again

It was made not const to modify it internally. But it caused problems
in CoCoALib and having const ref is the better interface choice.
nmzIntegrate: fixed a false dependency on verbose

If there is the .dec but not the .tri, the .dec is used also if only
the triangulation is needed. This did not work when the verbose flag
was not set, leading to an error "wrong dimension in file .tri".
nmzIntegrate: use CoCoA PolyRing_DMPI

The ring with DMPI is more efficient, but only allows limited exponents values.