Merge branch 'notsecure-split-video'
only allow call cancel during a pending invite
Merge branch 'JFreegman-avcancel'
Fixed video bitrate being set way higher than it should.

Video bitrate is set in kb/s not b/s.
Some video tweaks.
Tweaked conjestion control algorithm.

File transfers should now work better.
Fixed some more possible issues with file transfers/conjestion control.
Lowered video bitrate to 500kb/s and lowered audio buffer size.
Fixed segfault that happened because calls could be hanged up more
than once.
Fixed possible bug if more than one ringing msi packet was sent to us.
Fixed calling msi_reject more than once possibly causing issues.
Added install instructions for cross-compiling to Windows
Fixed spacing issue in the install instructions
remove pointer type warnings when building with mingw
Fixed tox_do_interval() returning value so high it broke A/V.
Merge branch 'windows-install-instructions' of https://github.com/nurupo/InsertProjectNameHere
Merge branch 'master' of https://github.com/notsecure/toxcore
Removed redundant encryption and asserts
Merge branch 'mannol1-master'
Core should no longer attempt to send data faster than the links can
carry it.