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

This reverts commit 37001778.

This reverts commit 8dab6d81.

(sorry)

It now detects if different replicas have different bias-factor

removed mention to a bug that is not actually there

Now all installers use a temporary directory

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Actually this should have been done together with 21be029e

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this is to test FIT_TO_TEMPLATE with TYPE=OPTIMAL and
domain decomposition (see #214)

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This is a nasty workaround. Since FIT_TO_TEMPLATE needs to
access forces stored in Atoms, it is necessary that they are kept up
to date. With this fix, there is an extra function
allowToAccessGlobalForces()
that switch off an optimization that would otherwise make the
forces wrong when running in parallel

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(thanks to @valsson)

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