wireguard-tools: bump to 1.0.20200513

wireguard-tools: bump to 1.0.20200513

* ipc: add support for openbsd kernel implementation
* ipc: cleanup openbsd support
* wg-quick: add support for openbsd kernel implementation
* wg-quick: cleanup openbsd support

Very exciting! wg(8) and wg-quick(8) now support the kernel implementation for
OpenBSD. OpenBSD is the second kernel, after Linux, to receive full fledged
and supported WireGuard kernel support. We'll probably send our patch set up
to the list during this next week. `ifconfig wg0 create` to make an interface,
and `wg ...` like usual to configure WireGuard aspects of it, like usual.

* wg-quick: support dns search domains

If DNS= has a non-IP in it, it is now treated as a search domain in
resolv.conf.  This new feature will be rolling out across our various GUI
clients in the next week or so.

* Makefile: simplify silent cleaning
* ipc: remove extra space
* git: add gitattributes so tarball doesn't have gitignore files
* terminal: specialize color_mode to stdout only

Small cleanups.

* highlighter: insist on 256-bit keys, not 257-bit or 258-bit

The highlighter's key checker is now stricter with base64 validation.

* wg-quick: android: support application whitelist

Android users can now have an application whitelist instead of application
blacklist.

* systemd: add wg-quick.target

This enables all wg-quick at .services to be restarted or managed as a unit via
wg-quick.target.

* Makefile: remember to install all systemd units

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>