Further work on the scons build:
Further work on the scons build:

- create command line variables for apr and apr-util locations (and the
  respective -config script), and an unused OpenSSL location
- add an error for unknown vars on the cmdline
- save the variables into .saved_config (svn:ignore on '.' updated)
- use ap?-1-config to get all the build flags, include dirs, etc and
  remove the hard-coded AP?_INCLUDE vars
- add some section markers for clarity
- move some platform-specific flags out of the Environment creation, and
  later add them unconditionally (for now)
- fix bug in DEPENDENT_LIBS (missing a space) and adjust the code for
  creating the @LIBS@ substitution variable

* trunk/: update svn:ignore property

* SConstruct: as above

jandre/serf,jandre/serf,jandre/serf,jandre/serf