Small changes for fixes to (#3014) and (#3019) - exception handling for when curl is missing being the main one

Need to include the file where artefact_get_references_in_html is
defined.

event handler.

Escaping with {} adds the database prefix on the front, and is for table
names only. Columns like "group" should be escaped with double quotes.

(cherry picked from commit 50d7897a)

Conflicts:

	htdocs/lib/web.php

(cherry picked from commit 7f7114e2)

Conflicts:

	htdocs/interaction/forum/theme/default/simplepost.tpl

It looks like MochiKit fixed a bug it had with IE, that made our
workaround no longer necessary. Happily, this patch seems to fix it all,
but that's no thanks to IE's terrible debugging tools.

Also check it before checking the user's quota, because it's a cheaper
check.

an error.

Thanks to Christoph Lischetzki

While I was doing that, internationalised the one for wall posts, and
refactored the generation of the help message to a function.

This makes them fit in better.
(cherry picked from commit 3d0f51f5)

(cherry picked from commit 3f9bdf5c)

http://mahara.org/interaction/forum/topic.php?id=131
(cherry picked from commit 4c2a22677c3ae886f0a0f76aea15a0a15eb02eb4)

Now they behave better, and respect the language pack search path. get_languages is cached.

Now the following locations are searched:

* docroot - the english language pack lives here
* directories in $dataroot/langpacks matching *.utf8
* anything on langpacksearchpaths

This makes $dataroot/langpacks the preferred place to install language packs, and makes langpacksearchpaths unnecessary for most people.

The upshot of all this is that it'll be much easier to install language packs - just download to $dataroot/langpacks and decompress :)

Thanks to discussion with David Mudrak, Nicolas Martignoni, I?aki Arenaza and others on the forums - http://mahara.org/interaction/forum/topic.php?id=120

Allow blog, blogpost and textbox blocktypes having links or manually created <img> tags to artefacts to have those artefacts counted as being within the blocktype, and thus within the view.

This is so if people manually link to or source artefacts within textual content, those artefacts will be downloadable when the view is shown to others.

Not backporting to 1.0 although the problem will most certainly exist there - the patch is just too big to trust on a stable release.