MAINT: get rid of some compiler warnings
- uninitialized pointer
- unused variables
- unused function
- ISO C prototypes
- `cimport *`
- useless cast before `snprintf`

Thanks for looking into this.

What compiler are you using? I may have a chance to try it out with clang.
 GCC 4.7.
 can you rebase this?
 @jreback done.
 can you quantify I guess how many warnings this removed? (as obviously still lots)
 I don't know, four, five? The code has moved on since I wrote this patch and I have no idea how many new warnings were introduced.
 this looks ok, but to be sure, can you rebase and push again? ping when green.
 Green!
 thanks!
