Add all the optimized NTRU

[mkannwischer]

Closes #48
I updated the m4 implementation of ntruhrss701.
I also added m4 implementation for the other NTRU parameter sets using optimized polynomial multiplication from https://github.com/mupq/polymul-z2mx-m4

The cycle counts for different approaches are below. Toom4 with a threshold of 16 gives the best performance for all schemes.

HPS509

Karatsuba

N	t	cycles
509	32	127179
509	16	119143
509	8	129116

Toom3

N	t	cycles
509	43	141586
509	22	120596
509	11	117546
509	6	174951

Toom4

N	t	cycles
509	32	110819
509	16	104477
509	8	112100

HPS 677

Karatsuba

N	t	cycles
677	43	248573
677	22	211035
677	11	204815
677	6	307912
677	3	530449

Toom3

N	t	cycles
677	29	209386
677	15	183694
677	8	224222

Toom4

N	t	cycles
677	43	208976
677	22	179414
677	11	174936
677	6	254515

HPS 821

Karatsuba

N	t	cycles
821	26	319727
821	13	271657
821	7	357646

Toom3

N	t	cycles
821	35	270843
821	18	274863
821	9	273797

Toom4

N	t	cycles
821	26	267783
821	13	229798
821	7	296095