Include all stylesheets in the theme hierarchy so the progress bar looks correct even when using a child theme.
(cherry picked from commit 6813e29bb6be7721921923644ed340ca80d03ea3)

This patch changes the behaviour to be thus:

- If the artefact now has no parent, we can safely remove all records in the APC
- If it does have a parent, insert a non-dirty record representing that relationship
- Mark all other rows referencing the artefact as dirty - we can't make any more conclusions at this point.

The cronjob will come through and clean up the dirty rows, as it always has done.
(cherry picked from commit bdca8220ebddf155bffa26c34f48c5795a774e0b)

How were we not doing this before?!
(cherry picked from commit 3e2222b01157bbfbbae7fd92ebc7c13f44b0a233)

(cherry picked from commit bcb10a104ec9dfa076decd85ea0f6b62fddd3cd0)

Copy plugin related files to directories without adding extra useless export/html/ directories to their paths.

Reverse the order of the stylesheets before smarty starts using them, so parent stylesheets are first.

Also destroy the session when creating a new user, to prevent strange session-out-of-sync problems. I think they only happen when a crash happens while creating a user account but you can't be too careful.

This probably needs calling in a few places, especially when the currently logged in user changes while the session is hanging around.

Hasn't been needed since before Mahara 1.0!

Conflicts:

	htdocs/lib/version.php

According to the documentation, getimagesize is slower, but will return the same result for filetype.
(cherry picked from commit 981e86f5)

Needed for all the copying I'm doing for the HTML export.

Mostly this is to cheaply get rid of the wall post form.

Now the default render_self for internal artefacts escapes their output, need to make sure the introduction is treated as HTML.

This required splitting up the export polling of artefact plugins into two steps - one where we establish what stylesheets are going to be needed, and the second for actually doing the export. This is because the second step writes out templates, so we have to know the stylesheets before this.

This required re-calculating the progress bar, those changes are reflected here too.