These functions were spread out over dive.c and divelist.c.
Move them into their own file to make all this a bit less monolithic.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
The Information tab shows the atmospheric pressure. Make this value editable
and also ensure that changes to it are undo-able.
Signed-off-by: willemferguson <willemferguson@zoology.up.ac.za>