channel: Remove code for automatically closing in channel_send_call

This was causing a segfault(reported in #1125) because channels are already
closed by `parse_msgpack` when the connection ends. Also fix the RPC stack
overflow error message
Merge PR #1127 'Fix segfault when calling methods in a client that already exited'
unittest: convert garray_spec.moon to lua
unittest: convert helpers.moon to lua
unittest: convert env_spec.moon to lua
unittest: convert fs_spec.moon to lua
unittest: convert path_spec.moon to lua
unittest: convert users_spec.moon to lua
unittest: convert preprocess.moon to lua
unittest: convert set.moon to lua
unittest: Remove remaining moonscript references
build: Remove moonscript as a third-party build dependency
unittest: Move FileInfo tests one level up
Merge #1128 'Drop moonscript'