check that player killed the monster before writing the memorial entry
refactor item::is_funnel_container

Use unsigned int as parameter, because it is compared against it_container::contains which is an unsigned int, too.
Return boolean and make the comparison in the function directly instead of after calling. At the same time update the maxcontains value.

And of course check for watertight container to fix #6411
Merge branch 'fix-blorg-monster-death' of https://github.com/BevapDin/Cataclysm-DDA into BevapDinFixes
Merge branch 'funnelllllls' of https://github.com/BevapDin/Cataclysm-DDA into BevapDinFixes