Testing more MOLINFO groups

Related to e45b88f3

[makedoc]

[makedoc]

Before c++11 we neede to use different timers on different systems.

C++11 defined a high resolution chrono class that should be portable.

List of modules used in the Portfile is now generated automatically
to better deal with user contributed modules. Variants are called
mod_xxx
where xxx is the module name.

In addition, a variant +allmodules has been added to enable all modules.
This variant is used in the travis file to make sure all modules are tested.

I am not sure it is worthwhile to also automatize other variants, so I think
this closes #193

COVAR allows using covariance matrix in calculating steps. BIAS_SCALE
was incorrectly overwriting the CENTER keyword.