These files were related to the original implementation of RMSD.
I think they have not been used for years, so I remove them.

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This is done only in the cmd interpreter

This should make the code slightly fast.

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Now all installers use a temporary directory

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Notice that even though we assume c++11 to be available
in PLUMED 2.4 I here protected the definitions so that
they are only available with a c++11-supporting compilers
(see comments in the code).

This should not be necessary in other parts of the code,
since autoconf is already checking that c++11 is supported.

This requires a few fixes:
- Replace -ansi with -std=c++11 in autoconf.
- Add a check that c++11 is supported in autoconf.
- Change flags for cppcheck.
- Remove travis configurations that would fail.

Additionally, I removed the check for 'explicit' keyword,
which is not needed with C++11.

Fixes #212

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Actually this should have been done together with 21be029e

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