* Clean up msg_wait_for_turns
* Clean up msg_get_next_packet
* Clean up msg_pre_packet
* Clean up DeltaSaveLevel
* Simple clean ups for msg.cpp
* Clean up NetSendCmdQuest
* Clean up NetSendCmdGItem
* Clean up NetSendCmdGItem2
* Clean up NetSendCmdPItem
* Clean up NetSendCmdChItem
* Clean up NetSendCmdDItem
* Clean up multi_send_packet
* Clean up msg_errorf
* Clean up i_own_level
* Clean up msg_free_packets
Pretty close to the original binary except for the first loop, which generates differently. (TODO comment added) There are also some questionable double address calculations, which hopfully clear up when the loop is fixed as well.
Also added enums `inv_body_loc` and `inv_xy_slot` to clean up a lot of magic numbers.