memory leak - removes do not get garbage collected

[yl2chen]

memory leak - removes do not get garbage collected

[mudream4869]

This code actually does not remove ALL networks.

_, all, _ := net.ParseCIDR("0.0.0.0/0")
ll, _ := trie.CoveredNetworks(*all)
for i := 0; i < len(ll); i++ {
	trie.Remove(ll[i].Network())
}

For example, if we first insert 192.168.1.0/24 and 192.168.1.1/32, then try to remove "all networks" by code snippet above, the trie will still leave 192.168.1.1/32.
The reason is that the CoveredNetworks function only return one network 192.168.1.0/24 in the case above. The Remove operation is implemented as just removing the node but if any child exists then the child will leave.
Test on playground ➡️ https://play.golang.org/p/7NRBI_zBYb5

[yl2chen]

@danmia Thanks for posting the tests to show the memory leak, and sorry I only got to investigating now, I have provided the fix and incorporated your test in the unit test suite.

[yl2chen]

I will leave the PR unmerged for some time, to give you a chance to independently verify that the memory leak upon removal is addressed, thanks!

[danmia]

Thanks for looking into it! It looks good in my local tests. This is super useful. Thanks again!