Add tracing support for important code

src/addressbook.cpp,
src/application-events.cpp,
src/cryptcontroller.cpp,
src/debug.h,
src/folder-events.cpp,
src/mail.cpp,
src/mailitem-events.cpp,
src/mapihelp.cpp,
src/mimedataprovider.cpp,
src/oomhelp.cpp,
src/parsecontroller.cpp,
src/rfc2047parse.c,
src/w32-gettext.h,
src/windowmessages.cpp: Add tracing support.

If DBG_TRACE is enabled this will trace function calls
and returns. As we don't really have a debugger this
can be important to understand differences in different
scenarios.

Big performance impact when enabled. Huge logs will be
created and the commit has a regression risk due to
lines like:

if (foo)

return X;

Where we now need:

if (foo)

{
  TRETURN X;
}

I hope I caught all this with my regular expressions and
manual review but this patch is very large,..