MdEditCodeBlock could not be local to the buffer

The code is loaded one time and this is good, the code is scoped to the
file and this is good, the command is global and this is bad. It would
be good to define the command in a file in `ftplugin` directory but to
do that we need to have access to the function to call...

For now this is a pretty acceptable solution, maybe in the future I will
find a better way :smile:
Fixed typo in a variable name