Added SEND_UDP_REQ and WAIT_UDP_REQ fetch states.
Parse 'content-range' from headers.
Purge 'complete' textures from the cache if they lack 'end of codestream' marker.
Added boostlevel/category to textureview display.
More diagnostic output.
Discard handling tweaks/bugfixes from v3.
Improved texture console progress bar visibility.
Shoehorned sgblacklist for server response status 499
Restored stat recording for LLViewerTextureList
Cleaned up lltexturefetch by excluding more unused code via #if