Smilies are now in a different directory. Also, TinyMCE seems to be
putting some attributes before the src tag, so match for that too.

Thanks to Howard Miller for the report.
(cherry picked from commit feb89b5fd038de1f8f29881814fd5b4c7971b62a)

The thumbnails are detected by the output filter, and information about them is sent to another object for storage, which is then asked about all the thumbnails it needs to include in the export later.

This catches thumbs on artefact/file/download.php and thumb.php, but doesn't yet seem to handle a couple of cases, like when a user has no profile picture.
(cherry picked from commit 6ee10e357e1ce41e9af4c2cd0c4456b82e9c356e)

(cherry picked from commit 4790ff5110a47afef76a830f097075d23b94dfb8)

Some smarter logic as suggested by Howard Miller.
(cherry picked from commit b63fa387fffe61b546842dc2fab4380510216dcb)

Both limits are of most underlying filesystems.

I haven't changed the <title> though I probably should at some point.
(cherry picked from commit 930d9a555d4b5d62d8a98757c3cc541dcebd26bf)

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.

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

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.

If just exporting a list of views for someone, don't bother with the summaries for the artefact plugins.

This allows them to inform code on the outside about what's going on. This is used by the export UI.

This makes sense, as people may have data in them and they will still want to get at that data even if their administrator disables the plugin.
(cherry picked from commit 61a608972d8a86daec2919a439533af826114021)

Don't use disabled artefact plugins when exporting HTML - if they're disabled, their data won't be in the export.

Uses a new helper class to do the gruntwork, and a lot of preg_replace stuff. It's a little bit hacky perhaps, but it's the simplest thing that could possibly work.