This PR contains the following changes:

• update all Nyx submodules
• fix for Better support for large map_size nyx-fuzz/packer#25
• configurable Nyx aux buffers size (useful if crash reports are truncated due to very long ASAN reports; see: add support to configure aux buffer size via args nyx-fuzz/QEMU-Nyx#52)
• NYX_VM=1 is set by default as env var
• certain information on the snapshot and the virtual machine state are now also written to a yaml file, which can be later processed by the fuzzing frontend (see: add yaml serializer for snapshot meta data nyx-fuzz/QEMU-Nyx#53)
• other minor changes and fixes