This will decrease the number of pull requests from PlumedBot.

Currently, everytime a file is updated and someone forgets to run
headers.sh, the headers are outdated. With this change, this will happen
once per year. PlumedBot will thus mostly fix erroneous copyrights
(rarely happening).

Plumedbot pull request

This commit contains changes automatically generated by plumedbot on Travis-ci.

Builds are faster on travis. Notice that all developers
recompile the code without this option, so in order to check if the
dependency options are fine we really do not need travis-ci.

with 315e6746

Strings like "x(abc)" where erroneously considered as equivalent to "(abc)"

Code results unchanged

This commit contains changes automatically generated by plumedbot on Travis-ci.

Fixed partial_tempering with gromacs 5 convention. Old behavior can be
forced with --gromacs4 option.

make clean was not correctly cleaning plumed executable

Thanks to Qingh Liao

correct definition of G vector in the documentation. A 1/gamma factor was missing. The actual calculation was correct and it remained unchanged.