Added functions to send custom packets

SendLosslessPacket doesn't work yet for some reason
Some work on events for custom packets
Added a simple function to get tox's data
Merge branch 'master' of https://github.com/Impyy/SharpTox

Conflicts:
	SharpTox/Core/Tox.cs
Merged from master and fixed conflicts
Packet events should work as well now
Changed the target framework back to 4.0

Also reverted any changes to .travis.yml. This should fix the travis-ci
build.
Added toxencryptsave functions
All of the new encryption functions should work
Updated the example
Added OnConnected and OnDisconnected events
Simplified some code
Throw an exception when trying to load encrypted data with tox_load
Implemented all avatar functions. And now we wait!

Waiting for this to be merged:
https://github.com/irungentoo/toxcore/pull/1029
Removed some image formats
FIxed array size related stuff

how silly of me
Updates to match core changes

See also:
https://github.com/irungentoo/toxcore/commit/80fdfbad07a7ab29dce86e862ae8429c241d5ce3
and
https://github.com/irungentoo/toxcore/commit/d2640103649b4513d2fc4d7bbb291fa941023ebf
Added IsOnline and changed some other small stuff
Some cleaning
Some updates for the new(ish) groupchats