FIX -Wconversion warnings for src/nvim/cursor_shape.c
add -Wconversion flag for src/nvim/os/channel.c
FIX -Wconversion warnings on src/nvim/os/channel.c
remove duplicated map.c from src/nvim/CMakeLists.txt
add -Wconversion flag for src/nvim/os/fs.c
TRIVIAL: fix trailing blanks in src/nvim/os/fs.c
FIX -Wconversion warnings in src/nvim/os/fs.c
sort files in alphabetical order, for better reading
add -Wconversion flag for src/nvim/os/input.c
fix -Wconversion warnings for src/nvim/os/input.c