[UPDATE] Better error handling for the IncludeViewhelper

If the Package/Controller is unknown the whole site will just show a big TYPO3.Flow
error message. This patch introduces the viewhelper argument "exceptionAs", this will make
it possible to display a custom error message in place of the plugin.

<mdc:include package="Kollode.TestPlugi" controller="Standard" action="index" exceptionAs="exception">
	<div data-alert class="alert-box alert">{exception.message}</div>
</mdc:include>
[FEATURE] Configure a custom 404 page

At the moment the user would just get a ugly 404 error, if
the the requested page dosen't exists. This patch makes it
possible to configure a fallback page that should be used
and only display the ugly 404 error if the fallback page is not
configured or dosen't exists either.

Scriptme:
  MarkdownContent:
    errorHandling:
      404: '404'
[FIX] Setting InMenu to false will result in a Exception

If InMenu or Visible is set to False no Meta information will
be set for the page array and the rendering of the menu fails
as soon you try to access a index other then children.

Don't add pages to the array if they are set to InMenu/Visible False
Merge pull request #3 from Kollode/errorHandling

[UPDATE] Better error handling for the IncludeViewhelper
Merge pull request #4 from Kollode/menuBugfix

[FIX] Setting InMenu to false will result in a Exception