Just doing things in more conventional way.

Don't assume that the params array is always present.  Even for methods.

Fixes #494

Convert latin1 escape sequences into UTF-8.  By default they resulted
in ASCII-8BIT (binary) encoding, which wasn't compatible with UTF-8,
resulting in error.

Added wrapper encoding method to cope with Ruby 1.8 which has no
builtin encodings support.

The tests file is now also a pure ASCII file, so no funky encoding-stuff
happens there.

Fixes #491

To handle the more complex nesting logic of the guide headings
and rendering of HTML, keeping the GuideToc class itself a lot cleaner.

It's a list, and should me marked up accoringly.

Turn GuideToc into instantiable class, so we can make use of
instance variables, refactor the logic into several helper methods and
avoid passing lots of arguments around.

Add tests for --guides-toc-level=1, 2, 3.

To be named more similarly with --guides option.

Improve the docs of the option - shorten lines and make the effect
of different argument values plain obvious.

The new `--guide-toc-level` option, which defaults to 2, controls what
heading levels will appear in guides' tables of contents. Specifying
`--guide-toc-level=N` will result in headings at or above <hN> being
included in all guides' TOCs. Choosing a `guide-toc-level` of 1 disables
the TOC entirely.

DeprecatedTag: fix typo in message

Fixed typo in README.md: Mediawiki → MediaWiki

Update README.md

So the logic for rendering the HTML is contained in one spot.

Avoiding passing it to almost every method.

We can now also implement an is_new? method that initializes the
lookup hash by itself when needed.

Just a shorter way to express the same thing.

The tooltip creation is really not the task for the Versions processor.
Moving it back to Tag::New were it was initially.

Correct link

Only add the @since annotation for params that were introduced after the
method itself was added.  When doing so, only consider the positions of
parameters, as they might be renamed between versions.

When method has explicit @since tag, then no param since tags are added.

Also implement #respond_to? on NullObject.

Nothing really good to do in this situation, but at least avoid
crashing.

Refs #475

List all the contributors + those who have posted 5 or more issues.

rake bump

    Bumps the minor version number by one.

rake bump["6.0.0"]

    Bumps to the specified version.

The version.rb file gets updated and committed.  The commit gets tagged
with the same version number.

So it's easy to find and update in there.

Extract it from the run of jsduck --version.

A regression introduced by the previous enhancement of Basic warning
class.

Helpful for debugging purposes.