Problem: The 'langnoremap' option leads to double negatives. And it does
not work for the last character of a mapping.
Solution: Add 'langremap' with the opposite value. Keep 'langnoremap' for
backwards compatibility. Make it work for the last character of a
mapping. Make the test work.
Problem: Cannot map <M-">. (Stephen Riehm)
Solution: Solve the memory access problem in another way. (Dominique Pelle)
Allow for using <M-\"> in a string.
