mmcgrana/gobyexample

Fix a few small typos.

Example shows methods being called on r1 (type Rand) not s1 (type Source).  Fix comment to reflect this correctly.

url-parsing: Use net.SplitHostPort

Use [net.SplitHostPort](https://godoc.org/net#SplitHostPort) instead of
strings.Split. This is the more correct way to split the host and port
as well as working with IPv6.

Typo correction

It's technically the same function being called and therefore run
twice.

Ref #90

At this point we're probably not going to add major new examples to
Go by Example. Remove the todo-ish looking list from examples.txt to
avoid implying otherwise in that file.

gofmt no longer supports `tabs` and `tabwidth`, but we still require
exactly-4-space tabs to preserve the narrow layout on gobyexample.com,
so re-implement this functionality with sed.

Clearly we were just able to read the content via ioutil.ReadFile but for consistency I think it would be better to call check(err) after the call to os.Open("/tmp/dat") on line 34.

Tools like errcheck (https://github.com/kisielk/errcheck) will complain about uncaught / unhandled err's. Also can we really be sure some 3rd party process didn't nuke '/tmp' during execution :-)

In most cases users will format and parse times using the constants
provided in package time. Show these first before getting into custom
example-based formats.