code.

by Rasterman).

- remove some unnecessary parameters to internal functions
- tests for cert extensions

the first theme data is requested; that way, the themed system colors
are set correctly from the start, and not just after some theme data
was requested.

- rearrange prototypes according to the DLL they're in, to make
  comments correct

actions. This allows us to make sure actions and custom actions
flagged to run only once, actually run only once.
Also clean up some of the numeric constants in custom.c using the
defined values from msidefs.h.

Improve trace in the unicode version.

dots or spaces.
Tweak the previous CreateDirectory() tests so we get more information
in case of a failure.