New release 0.20.0

Breaking changes

• Use bitflags. (3c08f7f, 5072f3a, 9271b33, 8564ed9, e26b489, b337e00,
  386470f, 99bd9d2, 590411d, 6f63c6b)
• bond: Convert InfoBond::Mode into an enum. (3e16f9c)
• ipvlan: Change mode type from u16 to enum. (396d4b0)
• link: Renamed LinkAttribute::NetnsId to LinkNetNsId. (528905c)
• mac vlan/vtap: Changed MAC VLAN/VTAP mode from u32 to enum. (b23b165)
• bridge: Change InfoBridge::VlanFiltering from u8 to bool. (de0f47a)

New features

• Added InfoData::IpVtap. (a8d125c)
• impl From<IpAddr> for RouteAddress. (984b358)

Bug fixes

• link: Check buffer length when parsing NLAs. (a543bb7)
• link: Expand the buffer before parsing stats data from old kernel. (4d5f819)