configure:
- added intel compilers to the list of standard compilers
- added a check that stops the configuration if --enable-almost is set but almost is not found
configure:
- if enable-gsl is used and gsl are not found stops with error
- give a warning if a default ON option cannot be activated
configure:
- it says if plumed will be compiled with MPI or not
wget should be already present on travis
Added -O3 and lapack to travis file
cleaner travis file

I removed all the commands to install latex.
Just as a secure copy, I leave the commands in .travis.install.doxygen
fix lapack for travis
Fixed phase in diagMatrix

Before this fix the phase was chosen enforcing the sum of the elements
of each eigenvector to be positive (see dd4bd09bf).
This does not work well when the
sum is numerically close to zero for some symmetry. With this fix I
set the first non-zero element of each eigenvector to be positive.
Hopefully it is more robust and make results better reproducible
for regtesting
changelog