cc: @carlocamilloni

See #416

(backports)

See #407

LDFLAGS were overwritten by mistake by CFLAGS when doing coverage

defined then just use one thread

@giovannibussi right?

- dumpgrid
- pca
- mds

this makes the link visible also when browsing with a mobile

All atoms were erroneously requested also after the first step.

when using DEBUG, detailed timers were always shown by mistake.
Now they are only shown when using flag DETAILED_TIMERS

removed sentence about NOSPLINE

https://groups.google.com/d/msgid/plumed-users/4bdade66-5dde-4748-b3c2-3c6155906b69%40googlegroups.com?utm_medium=email&utm_source=footer

Small fix: do not push manual when building from a pull request