Remove "Unknown inventory identifier" deserialization errors, because they can break forward compatibility

Switch the license to be LGPLv2/later, with small parts still remaining as GPLv2/later, by agreement of major contributors

The huge item definition and item namespace unification patch (itemdef), see http://c55.me/minetest/wiki/doku.php?id=changes:itemdef

Make ToolItem and MaterialItem to convert names by aliases at creation time too (necessary for eg. crafting)

A spurious semicolon after the conditional checking for the drop count
to be not higher than the owned count caused the subsequent
    count = getCount()
to be always executed. Fix by removing the extra semicolon.