Target 1: Complete methods related to Seifert Matrix implementation.

Methods implemented include:
1. _braidwordcomponents
2. _braidwordcomponentsvector
3. homology generators
4. Seifert Matrix
5. link number
6. is_knot
7. genus
8. smallest_equivalent
9. signature
10. alexander_polynomial
11. arf_invariant

The methods have also been documented and examples included. I have tried to cross check with as many examples as possible. If you find something inconsistent please comment. I hope that completes the implementation related to Seifert Matrix :)