I added a forwards and a backwards recurrence routine which work on a CHUNK of x-values. This is for performance reasons: a recurrence loop does not vectorise, so we put a small x loop inside that the compiler can vectorise.
Merge branch 'devel' of https://github.com/baudren/class into devel

* 'devel' of https://github.com/baudren/class:
  I added a forwards and a backwards recurrence routine which work on a CHUNK of x-values. This is for performance reasons: a recurrence loop does not vectorise, so we put a small x loop inside that the compiler can vectorise.
corrected small bug in C_l^lensing leading to erro for some values of redshift
fixed bug in sign of transfers with new function trapezoidal_mweights, and added density*lensing correlations (dl)
default value of Neff set to 3.046, and more explicit error message when unrelaistic values of omega_b or Neff are passed
tol_tau_approx lowered to 1e-10 to render equal approx switching times highly unlikely
restored same sign conventions for E as in camb
several bug fixes, add lensing-density correlation, vectorize recurrence
* devel:
  restored same sign conventions for E as in camb
  tol_tau_approx lowered to 1e-10 to render equal approx switching times highly unlikely
  default value of Neff set to 3.046, and more explicit error message when unrelaistic values of omega_b or Neff are passed
  fixed bug in sign of transfers with new function trapezoidal_mweights, and added density*lensing correlations (dl)
  corrected small bug in C_l^lensing leading to erro for some values of redshift
  I added a forwards and a backwards recurrence routine which work on a CHUNK of x-values. This is for performance reasons: a recurrence loop does not vectorise, so we put a small x loop inside that the compiler can vectorise.