First version of HTTP bandwidth throttling.

Adds throttling based on on average bandwidth usage per HTTP service.
Since only HTTP textures are using this, they are still starved by other
services like inventory and mesh dowloads. Also, it will be needed to
move the maximum number of connections per service the to the PerService
class, and dynamically tune them: reducing the number of connections is
the first thing to do when using too much bandwidth.

I also added a graph for HTTP texture bandwidth to the stats floater.
For some reason the average bandwidth (over 1 second) look almost like
scattered noise... weird for something that is averaged...
Bring back "Refresh Grid Info" button in grid manager.

If you clicked on 'Add' and then filled in the fields that say
'<required>'.. and then click on OK... Then all the URL's stay blank and
there is no way to fix that anymore (short of deleting the entry first
and NOT filling in the required name?!).

I added the button back to get the URL, at any time. Much more clear.
While at it, I added some tool tips and renamed 'Add' to 'Create'
because it confused the hell out of me to have a grid selected and then
needing to press 'Add' below that.. as if you add something to the
selected grid (Better would be to have the Add button above the
selector, or even be part of the selector drop down).
Merge remote-tracking branch 'aleric/master'
Merge remote-tracking branch 'lirusaito/master'
XML corrections

French corrections
Correct Aleric's mistype of tool_tip