Currently we use the same_cylinder() function to determine
which cylinders should be edited in a multi-dive edit. Make
this more flexible by introducing a flag-set, such that
the undo-command can select which cylinders are considered
as equal:
- same type
- same pressure
- same gas mix
- same size
Currently both undo commands use same type, pressure and
gas so that the behavior stays unchanged.
The future goal is to split the cylinder-edit undo command
into different commands so that when, for example, editing
the type only the type is considered by not the gas mix.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>