deleted unused defines in vim.h  #772
Prevent null-pointer deference during vim_eval  #785

If the eval_expr call in vim_eval returns NULL, a null-pointer deference
would happen a few frames down, in vim_to_object_rec
Add function attributes to functions in memory.h  #811

Add missing function attributes in memory.h. Fixes #806
Declare garray iterators in the for() scope where possible #819