Intending to use the same logic in RKellyParser.

In an attempt to replace Esprima with RKelly, I created an adapter
to convert the RKelly AST into Esprima AST.

The backwards-compatibility fix for code like:

    Here's the code example:<pre><code>
    alert("Blah");
    </code></pre>

was a bit too lose.  So tightened it up to only apply in case
where the <pre> or <pre><code> is at the end of line.

Fixes: #380

There was a conflict with one method looping over array while
other deleting items from it at the same time.

Fixes: #378

The existing code for skipping constructors had become outdated.

Instead the MemberTag class now has two helper methods:

- member_link - for rendering member name as a link.
- member_params - for rendering the params list.

Most of the complexity was really related to rendering the
method signature - all this logic is now in Tag::Method class.

Some leftover from old times - not needed at all.

Without this 1px shift some of the icons will be missing pixels from the
bottom.

Member icons are now defined in member tag classes.  There the
:icon field defines the icon file which is included to the docs
app resources and an appropriate CSS gets generated.

In Ruby 1.8 it happens that MemberTag is loaded twice and the
constants in it get redefined, and trigger a warning.

A bunch of these were used in the old Touch welcome page, which
no more exists.

Some were leftovers from various style changes throughout the
Docs app history.

Fixes: #376

Previously these old-style links were rendered disfunctional.

Instead use the already defined :tagname field.

Was forgotten in at previous refactor.

Plus a typo.

With this we completely get rid of the @merge_context variable,
and all the merging happens in Tag::Class or MemberTag subclasses.

A bit of a duplicated code in Cfg and Property, but we get rid of
the explicit check for :cfg/:property/:css_var in Type class.

This contains a fix for the changed newline handling in IE10.

Fixes: #373

Only use the :method category in @merge_context.

So no more does one need to choose between two types when creating
his own member type.

The only problem at the moment is that I needed to add explicit check
for :cfg/:property/:css_var to Tag::Type#merge.