Fixes pr

[lanrat]

• typos
• lint warnings
• error checking
• use go naming conventions for internal types
• Fixes server.Shutdown() should print errors #72

[grandcat]

Thanks for your contribution.
However, Windows test is failing since this change.

[lanrat]

Thanks for checking out this PR.

The Windows test that is failing is below:

$ go test --parallel=1
go: finding github.com/pkg/errors v0.9.1
2021/04/26 18:25:21 [zeroconf] no suitable IPv4 interface: not implemented on windows/amd64
2021/04/26 18:25:21 [zeroconf] no suitable IPv6 interface: not implemented on windows/amd64
panic: while registering mdns service: no supported interface
goroutine 8 [running]:
github.com/grandcat/zeroconf.startMDNS(0x680e00, 0xc0000461e0, 0x22b8, 0x6465a8, 0x12, 0x6455a7, 0x10, 0x642786, 0x6)
	C:/Users/travis/gopath/src/github.com/grandcat/zeroconf/service_test.go:25 +0x323
created by github.com/grandcat/zeroconf.TestBasic
	C:/Users/travis/gopath/src/github.com/grandcat/zeroconf/service_test.go:43 +0x123
exit status 2
FAIL	github.com/grandcat/zeroconf	0.080s
The command "go test --parallel=1" exited with 1.

The test is failing for Windows in this PR because of the additional error checking. Previously the test would fail silently because the errors were not checked. The reason for the failure was not introduced in this PR, it was just made visible.

The test can be updated to ignore the error on Windows, or fixed to better support Windows. Both were initially out of scope for this PR.

@grandcat what are your thoughts?