builtinurl: initial working attempt

Note that the builtin URLs are disabled by default. To activate,
"builtinurl enable" or use the builtinurl_enable API.

See .../extras/http/sample.md for some Hugo-friendly .md w/ embedded
Javascript that accesses the builtin URLs.

Type: feature

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I6d82d9292c41d6d2d90be73ba8a1a043fb20c986
diff --git a/extras/http/setup.http b/extras/http/setup.http
index 3b8da57..78b7a2f 100644
--- a/extras/http/setup.http
+++ b/extras/http/setup.http
@@ -3,4 +3,5 @@
 set int ip address tap0 192.168.10.1/24
 set int state tap0 up
 
-http static server www-root /scratch/fdio-site-fork/public uri tls://0.0.0.0/1234 cache-size 10m fifo-size 2048
+http static server www-root <path> uri tcp://0.0.0.0/1234 cache-size 10m fifo-size 2048
+builtinurl enable