Added new controls to Network Preferences

Adds Texture Bandwidth slider
Adds Use HTTP for Inventory and Textures checkboxes.
Also, swaps out the bandwidth slider for a new Z Offset slider on quick settings, as bandwidth sliders should be set and forget, there is no modern need for them to be changed so frequently.

[Note to translators: please examine the network preferences after this update, controls have been moved and may now overlap.]