changed ref to subpage and added comment on FIT_TO_TEMPLATE

(no real change, the relevant files where not modified in gmx)

Added possibility to remove checks such as
"-ansi" and "-Wall" (--disable-basic-warnings)

Changed name of temporary files from test... to conftest...
(consistent with autoconf behavior)

plumed core can be compiled without these.

With this change it is necessary to solve a but in the script building the
list of modules to be tested. I took the occasion to simplify it.
Now, all the optional modules are checked, but if a directory is
not present in regtest/ that module is ignored.

Conflicts:
	src/vesselbase/ActionWithVessel.cpp

(cherry picked from commit ab117d79)

Conflicts:
	src/vesselbase/ActionWithVessel.cpp

This is for vessels.  Basically you now can't create a FunctionVessel
without adding a description to the manual of the quantity it
calculates

This test is very sensitive to numerical errors and is thus
not a good test of the code.  The functionality that is
being tested here is tested elsewhere.

Note changes to many regtests are because of changes in labels of
components

A component called "bias" is needed for replica exchange to work properly

Notice that latex cannot be used in captions

Conflicts:
	src/tools/BiasRepresentation.cpp

(cherry picked from commit 15823407)

Conflicts:
	src/tools/BiasRepresentation.cpp