v0.1.7

Closed issues:

• #482 CMake can't detect and compile ToxAV on OSX

Merged PRs:

• #521 Fix appveyor script: install curl from chocolatey.
• #510 Fix list malloc(0) bug
• #509 Fix network malloc(0) bug
• #497 Fix network
• #496 Fix Travis always succeeding despite tests failing
• #491 Add crypto_memzero for temp buffer
• #490 Move c_sleep to helpers.h and misc_tools.h
• #486 Remove empty line in Messenger.c
• #483 Make BUILD_TOXAV an option and fail if dependencies are missing
• #481 Remove dependency on strings.h
• #480 Use VLA macro
• #479 Fix pthreads in AppVeyor build
• #471 Remove statics used in onion comparison functions.
• #461 Replace part of network functions on platform-independent implementation
• #452 Add VLA compatibility macro for C89-ish compilers.