sample_data_folder/sniffer/umsg_sniffer:

- Added sample umsg_sniffer plugin log.

autorun/client/sniffer.lua:
- Updated todo list.
- Updated convar list.

sniffer/addons/net_hook.lua and sniffer/addons/net_sniffer.lua:
- Updated hook names to be more verbose.

sniffer/addons/umsg_hook.lua:
- Added file, this provides the 'SnifferUserMessageReceived' hook.

sniffer/plugins/umsg_sniffer.lua:
- Added file, this provides logging for received user messages.

sniffer/sniffer.lua
- Added 'sniffer_logging_verbose' to toggle verbose logging. (Defaults
to 1)
- Added 'SNIFF.IsLoggingVerbose()' for checking if logging is in verbose
mode, need to add support for this in the default plugins...

sniffer/addons/manager.lua:
- Added file, it's blank with a header, just a reminder to complete.