Re-implement functions and functions form R^n into R^m

[rafaelrojasmiliani]

At the commit 8b53d24, functions are only intended to represent curves. However, in order to reresent maps between manifolds we can expand this type into maps from R^n into R^m.

• [ ] Define an abstract class called domain with the following pure virtual methods
  • [ ] With equal operator
  • [ ] with "contain" method which accept a point
  • [ ] with "contain" method which accepts another domain
  • [ ] with dimension method "dim"
  • [ ] make is inheritance helper
  • [ ] clone, move_clone
• [ ] redefine the base function class
  • [ ] it has a domain as a member
  • [ ] Modify its value member. Now value should accept an array of elements of its domain (Vector<double, N, 1>)
  • [ ]