Typos in tutorials
some cleaning in the code
NOE: stadardized the output files name
to_string doens't work with some version of icpc and g++
Changed subpage to ref
fixes in doc

changed ref to subpage and added comment on FIT_TO_TEMPLATE
Fixed name of module page
Gyration: documentation
Gyration: documentation

(cherry picked from commit d523213f648d6a10307932022c5aaba1fa93def4)
Merge branch 'v2.0' into v2.1
Fixed valgrind issue in regtest
Merge branch 'v2.1' of github.com:plumed/plumed2 into v2.1
Merge branch 'v2.1' into v2.1-hrex