Add support for TinyGo

[efraimbart]

Resolves #951

[VojtechVitek]

LGTM. Thank you!

Can someone help me test this with TinyGo?
I'll wait for few more reviews and we can merge 👍

cc @angelofallars @cxjava

[cxjava]

build as expected, no error.

---

BTW:
when I want to use middleware in tinygo, it will failed because of https://github.com/go-chi/chi/blob/master/middleware/profiler.go, not package net/http/pprof for tinygo.

	r := chi.NewRouter()
	r.Use(middleware.CleanPath)
	r.Use(middleware.RealIP)
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)

error output:

../../../go/pkg/mod/github.com/go-chi/chi/[email protected]/middleware/profiler.go:6:2: 
package net/http/pprof is not in std (/Users/user/Library/Caches/tinygo/goroot-598d56643c1f2b0a17cb7ed7f5003addae1fc3ee5af904a1c5356bb7118a4988/src/net/http/pprof)

@efraimbart Maybe we also need to exclude middleware/profiler.go when use tinygo. CC: @VojtechVitek

[efraimbart]

Unfortunately I'm not familiar with middleware or what would happen if it's excluded.

[cxjava]

No worry, I can create other PR to fix the middleware build.

[VojtechVitek]

Thanks, I'll merge both #978 and #982.

LGTM