Update math/ntl to version 6.0.0

Differences from previous version (5.5.2):

	2013.02.15: Changes between NTL 5.5.2 and 6.0

	Replaced the old template-like macros for vectors, matrices, and pairs
	with true template classes:  Vec<T>, Mat<T>, and Pair<S,T>.  For
	backwards compatibilty, all the names that were used in previous
	versions (e.g., vec_ZZ_p, mat_ZZ_p) have been replaced with
	appropriate typedefs.

	For many years, I resisted the temptation of using templates, because
	compiler support was very inconsistent.  But that no longer seems to
	be the case.

	This change, while rather sweeping, should create very few, if any,
	incompatibilities with existing software.  The biggest issue would be
	for software that uses the old template-like macros:  such macro
	invocations can simply be replaced with appropriate typedefs.

	Made the conversion interface more complete and uniform.  Also, using
	template notation, one can and should now write conv<ZZ>(a) instead of
	to_ZZ(a) (for backward compatibility, all the old names to_XXX are
	still there, but many new conversions are not available under these
	old names).  There are many new conversions provided.  Moreover,
	whenever there is a conversion from a ring R to a ring S, there is a
	corresponding, coefficiet-wise conversion from the polynomial ring
	R[X] to the polynomial ring R[X].

	In addition, using the template mechanism, there are generic
	conversions for vectors and matrices.  For example, if there is a
	conversion from S to T, then there is automatically a corresponding
	component-wise conversion from Vec<S> to Vec<T>.

	Introduced a more general mechanism for accessing GF2's in packed
	structures via indexing (see the class ref_GF2 in the GF2 module).
	Employed ideas from David Harvey to make the single-precision FFT
	faster (about twice as fast in many cases).  This speeds up many
	higher-level operations.

	Fixed all known bugs.
Note update of math/ntl to version 6.0.0
Initial import of HElib, a library to perform homomorphic encryption,
into the Packages Collection.

	HElib is a software library that implements homomorphic encryption
	(HE).  Currently available is an implementation of the
	Brakerski-Gentry-Vaikuntanathan (BGV) scheme, along with many
	optimizations to make homomorphic evaluation run faster, focusing
	mostly on effective use of the Smart-Vercauteren ciphertext packing
	techniques and the Gentry-Halevi-Smart optimizations.
Add and enable security/HElib
Note addition of security/HElib