Fixed MSVC makefile use of /Wp64 flag.

Problem:    When using ":earlier" undo information may be wrong.
Solution:   When changing alternate branches also adjust b_u_oldhead.

fail with tiny features.

Problem:    Calling a function through a funcref, where the function deletes
            the funcref, leads to an invalid memory access.
Solution:   Make a copy of the function name. (Lech Lorens)

Problem:    Invalid memory access when doing thesaurus completion and
            'infercase' is set.
Solution:   Use the minimal length of completed word and replacement.
            (Dominique Pelle)

Problem:    "vim -r" crashes.
Solution:   Don't use NULL pointer argument.

finish, no need for the user to press Enter.

A few minor changes.

Attempt at a fix.