htod - convert C .h files to D import files

[Lionello Lunesu]

I have found some other issues with htod, but am reluctant to post them. 
  Don't want Walter's focus to shift to other tools. (Who am I to worry 
about Walter's focus? :S)

Anyway, here are some things to keep in mind when using htod:

* signed char => sbyte
* wchar_t not known (it's built-in in vc?)
* void func( void (*callback)(void) ) => void func( void 
function(...)callback );
* comments are 1 line off

L.