Remove AM/PM from time formatting (to be Locale neutral)

... sync all format strings for time input/output to 'hh:mm:ss'
... remove any 'AM/PM' time formats
... remove tr() commands from time formats (since 'hh:mm:ss' is
reasonable around the globe)

... main reason: QT5 does not follow the pure formatting rules any more
(like QT4), but considers the system.locale in formatting as well (so
for system which have no AM/PM, even if the format string is set, the QT
routines ignore that - having some side effect on GC)
Merge pull request #949 from Joern-R/pull3

Remove AM/PM from time formatting (to be Locale neutral)