add new function casimir_integrate, that returns the integrals A,B,C and D for
p=TE,TM
remove swap files
* Add a function to integrate every component of a vector
* Functions integrate now f(x)*exp(-x) instead of f(x)
* Functions now return associated Legendre polynomials Plm or spherical
  harmonics evaluated at phi=0 for x=cos(theta)
* New function, that returns Yl1m, Yl2m, dYl1m and dYl2m
* Added comments.
* Added comments.
* Deleted obsolete code and functions.
* The integration is now done as a vector to increase speed.