Bug 16400: Let's hack the fixFloat plugin to fix our needs

Bug 16400: Let's hack the fixFloat plugin to fix our needs

On comment bug 11088 comment 2, Owen explained the problem with the
fixFloat toolbar. Since we have a hidden div, the plugin does not manage
to place the toolbar correctly.
In order to make it work, this patch adds some changes to the plugin to
add the ability to define our own offset.
When the div is extended (+, filteraction_on), the offset should be
updated to move the toolbar. Same when the div is folded (-,
filteraction_off)

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit c1f101e86c717ceaccf781de0f1c05dc23c8272a)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>