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.]
This introduces some API changes, like the new LLDirIterator,
that causes changes elsewhere.
It also include Log Linden's cache changes that aren't in
viewer-development yet that increase the maximum cache size
to ~10 GB.
Also removed some code from the Mac/windows code in
indra/plugins/filepicker/llfilepicker.cpp that shouldn't
be in there anymore (send_agent_pause/resume and updating
the LLFrameTimer stuff).
