Simple fix to the documentation

[Tobychev]

changed from "dmod" to "mod_dir" and similar in one example

[szaghi]

Tomas,

I am sorry, I have just pushed the version I am using that is different from the one you have forked...
I cannot easily merge your pull.

I try to patch my code with your modifications.

[Tobychev]

Dang! I pulled just before to make sure I was up to date too :(

Oh well, I'll go check out what's new now :)

[szaghi]

Tomas,

I have just pushed the new FoBiS with the possibility to specify PreForM output dir. Anyhow, I was wrong: if not specified the sources preprocessed with PreForM are removed after they are used. Now, if you specify a directory they are saved...

The new feature is not documented... to use it just use the CLI switches --pfm_dir or -dpfm or put inside fobos pfm_dir = your_preferred_dir/. Note that as mod_dir and obj_dir, pfm_dir is relative to build_dir. If it is not defined the previous behavior is valid: the preprocessor outputs are removed after used.