Filenames in both warnings and log messages are converted to windows
style if platform is Windows.

Warnings begin again with "Warning: ".

It just made the code harder to read without adding any real value.

Plus it's better to measure the performance using system 'time' command
anyway.

Internally UNIX style filenames are always used, but for printing
out it makes sense to use the platform-specific notation.

Added small helper class to detect OS.

Fixes scanning directories for .js files in Windows.

--meta-tags option can now accept either a path to file or directory.
And one can use the option multiple times to name several files
one-by-one.

More accurate, as it's not only Markdown. If one desires doing
Markdown-only, then he can include RDiscount by himself and do
whatever he wants.

Previously it was either builtin ones or user-define ones.
Now one can have a combination of the two.

Each meta-tag class is now responsible for rendering a block of all
meta-tags of same type, complete with title and everything.
The transform method has been replaced with to_html method that
converts array of meta-tag contents into output HTML. No more are
there @title and @hidden attributes.

When there's more than one file, pop up a menu with all files.

One can now write:

    @param {Object} [scope=this]

And the default value will be `this`.

Instead printing out a warning.

Avoid fatal crash - instead print out warning.

Previously the overflow rule was together with font-size:79.8%,
but that was only applied to Tablet examples.

Wrap all icons in index pages inside div. For touch examples, add
extra touch-examples-ui class to examples index page and adjust the
styling a little in CSS.

Modified origin commit by Nick Poulden by wrapping ExtJS welcome
page inside <div id="extjs-welcome"> similarly to Touch welcome
page inside <div id="touch-welcome">.  This way they're both
nicely wrapped and ExtJS welcome page doesn't get screwed up.