increase NodeList send buffer size by default to 128KB
output old size when notifying for send buffer size change
attempt to set send buffer size to 1MB
add a method to Agent for last read frame loudness
cast setsocktopt and getsockopt calls to fix windows build
ifdef to handle getsockopt format requirements on windows
Merge pull request #2510 from birarda/agent-loudness

add a method to Agent for last read frame loudness
add a button on DS admin page to kill all nodes
Merge branch 'master' of https://github.com/highfidelity/hifi
Merge pull request #2513 from ey6es/master

Added mono to stereo conversion to fix Linux audio.  Closes #2508.
Merge pull request #2514 from birarda/kill-node-button

add a button on DS admin page to kill all nodes
wait on broadcastThread before destroying AvatarMixer, closes #2499
Merge pull request #2503 from birarda/master

increase NodeList send buffer size to 1MB
actually attempt to change send buffer size
Merge pull request #2516 from birarda/master

actually change NodeList send buffer size
Merge branch 'master' of https://github.com/highfidelity/hifi
Formatting fixes.