Problem:    "safe" argument of call_vim_function() is always FALSE.
Solution:   Remove the argument.

Problem:    Expanding a file name "~" results in $HOME. (Aidan Shafran)
Solution:   Change "~" to "./~" before expanding. (closes #3072)

Problem:    Still a few K&R function declarations.
Solution:   Use ANSI function declarations (Hirohito Higashi)

Problem:    Memory leak with trailing characters in skip expression.
Solution:   Free the return value.

Problem:    The first argument given to 'completefunc' can be Number or
            String, depending on the value.
Solution:   Avoid guessing the type of an argument, use typval_T in the
            callers of call_vim_function(). (Ozaki Kiichi, closes #2993)

Problem:    Cannot use :unlet for an environment variable.
Solution:   Make it work.  Use unsetenv() if available. (Ken Takata,
            closes #2855)

Problem:    A timer may change v:count unexpectedly.
Solution:   Save and restore v:count and similar variables when a timer
            callback is invoked. (closes #2897)

Problem:    Assert functions don't return anything.
Solution:   Return non-zero when the assertion fails.

Problem:    No compiler warning for wrong format in vim_snprintf().
Solution:   Add printf attribute for gcc.  Fix reported problems.

Problem:    The terminal API "drop" command doesn't support options.
Solution:   Implement the options.