updated for version 7.4.269

Problem:    CTRL-U in Insert mode does not work after using a cursor key.
        (Pine Wu)
Solution:   Use the original insert start position. (Christian Brabandt)

Signed-off-by: Alessandro Vioni <jenoma@gmail.com>
updated for version 7.4.270

Problem:    Comparing pointers instead of the string they point to.
Solution:   Use strcmp(). (Ken Takata)
Signed-off-by: Alessandro Vioni <jenoma@gmail.com>
updated for version 7.4.271

Problem:    Compiler warning on 64 bit windows.
Solution:   Add type cast. (Mike Williams)
Signed-off-by: Alessandro Vioni <jenoma@gmail.com>
updated for version 7.4.272

Problem:    Using just "$" does not cause an error message.
Solution:   Check for empty environment variable name. (Christian Brabandt)
Signed-off-by: Alessandro Vioni <jenoma@gmail.com>