Adding semgrep yaml file

Merge pull request #24 from redmercury/master

This change modifies instances of the url github.com/majek/slirpnetstack

race detector: move tcpip.Stack initialization around to make race happy

tests: test if large UDP packets go through local forwardingpp

Fix buffer hand over between go routines in LocalFowardUDP by adding an extra copy

Update gvisor to v0.0.0-20201204040109-0ba39926c86f2020

Allow for forwarding large UDP packets - they may be fragmented

CC-236 Configurable dns host for @srv syntax

minor: sometimes in remote-fwd message we see nil as RemoteAddr

Merge pull request #23 from lnsp/log-quieter

minor: suppress local/remote-fwd logs on quiet

minor: support -version flag to query for code version

More detailed logging on address resolution failures

Fix #19 - change internal IPv6 from [2001:2::2] to [fd00::2] to adhere to RFC4193