Language module support added

I have added:
- The ":import" command (implemented by Adriaan de Groot).
- The "d" language module and "dmd" tool (from Lars Ivar Igesund).
- The get_var_attr() function (to avoid repeating the code to check for
  the "buildaction" attribute).
- The :toolsearch command makes it simpler to search for a list of
  tools.
- $BUILDLIB_ACTION and $BUILDDLL_ACTION for building libs and dlls with
  a different action.

I still have to add documentation in the user manual for all this stuff.
There are a few remarks in the reference manual already.

All this is in Aap 1.033, currently only in CVS.  But you can also get:

	http://www.a-a-p.org/files/aap-latest.zip

Please have a look at how it works and try it out.  I have made several
changes to the code:

- The ":import" command searches various "modules" directories for a
  module.  All found modules are loaded in the same scope.  The modules
  must take care of not defining things that have already been done by
  checking for the did_import_<name> variable.

- I removed the "build" actions from the "d" module and added a
  "d_build" action.  The "buildaction" of the object files is set to
  invoke this "d_build" action.  This is a generic solution for invoking
  the desired build action.

- I named the "d" module "dlang", to avoid a name conflict with a
  variable called "d".  There can't be a variable and a scope with the
  same name.

Hopefully I didn't break the already working code that others made.
Please let me know what should be improved!

-- 
How To Keep A Healthy Level Of Insanity:
18. When leaving the zoo, start running towards the parking lot,
    yelling "run for your lives, they're loose!!"

 /// Bram Moolenaar -- [email protected] -- http://www.Moolenaar.net   \\\
///          Creator of Vim - Vi IMproved -- http://www.Vim.org          \\\
\\\              Project leader for A-A-P -- http://www.A-A-P.org        ///
 \\\  Help AIDS victims, buy here: http://ICCF-Holland.org/click1.html  ///


-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf