CS2BACKBONE: fixed problem with printing out chemical shifts with parallel simulations
CS2Backbone bug in CHANGES
CS2BACKBONE: more prinout fixes
Changed analysis so that data are accumulated in update()

(backported from master).

@gtribello you might want to check if this is ok.
Notice that without this fix histograms accumulated in a replica exchange
simulation would include also data from other replicas, which is a bug.
I thus think this commit should be applied also to v2.0 and v2.1.

(cherry picked from commit 69578b2d34e60742372c713c8a3da7e51324ef06)
changelog
Merge branch 'v2.0' into v2.1
Merge branch 'v2.1' into v2.1-openmp
Added notes on file backup/restart/suffix
gmx5 patch fix: Plumed.h was included incorrectly, thanks Luca for spotting it
Fixed portability of Stopwatch

I fixed some probability issue in Stopwatch.
Before this fix, the macro used to check the presence of
clock_gettime was not properly recognized. Additionally,
gettimeofday was considered as compulsory, causing problems
on bgxlc (as pointed out by Teodoro Laino).

After this fix, both gettimeofday and clock_gettime
are searched and considered as optional. If present,
clock_gettime is used. Otherwise gettimeofday is used.
If none is present, time is just not measured.
changelog
configure: added the test for bz2 that is optional in almost and so
should be checked before almost in order to link it correctly.
configure: link almost to plumed
updated CHANGES
doc: install with almost update
Merge remote-tracking branch 'origin/v2.1' into v2.1-openmp