Add Cholesky-Matrix (C)

- Fraction-view works now fully correct (also with numbers > 1.0)

Fraction.js
 - if deno === 1 only print the numberator

MathHelper.js
- can convert any number (bigger then 1.0 for example) to an fraction. Also Integers can be converted

Matrix.js
 - calcCholesky (view web for more information to cholesky)

Matrix.html :
 - view C as Fraction or as Numbers
 - add button for cholesky