fix heatns compilation
Update README.org
@Trophime avaoid allocation x coordinates at each update, do it only once in
the constructor
@Trophime fix compilation
Merge branch 'develop' of https://github.com/feelpp/feelpp into develop
@Trophime It seems that the problem is fixed regarding the Eigen assertion in
case of fixed size matrices. Now I differentiate the case when the number of
columns is 1 and > 1.
Merge branch 'develop' into feature/explicit

Conflicts:
	feel/feelvf/ginac.hpp