* AutotoolsPackage: added configure_directory to permit build out of source. The configure script executable is now invoked with an absolute path. Modified a few packages accordingly.
* build_systems: functions returning directories are now properties
* build_systems: fixed issues with tcl and tk
* AutotoolsPackage: reworked recipe for autoreconf
* Update flex package url's and versions
The old sourceforge page for flex is now defunct. While version 2.6.0
still downloads fine, later versions are no longer hosted there.
Development continues on github. I've adjusted urls to point to this
new location.
In addition, from 2.6.0 onwards, a new naming scheme for releases seems
to have been adopted. I've created a url_for_version function to sort
this out.
* Change flex to an AutotoolsPackage
Also move the url_for_version function to the end of the package
definition.
* Implement the autoreconf function for flex
Package repositories now look like this:
top-level-dir/
repo.yaml
packages/
libelf/
package.py
mpich/
package.py
...
This leaves room at the top level for additional metadata, source,
per-repo configs, indexes, etc., and it makes it easy to see that
something is a spack repo (just look for repo.yaml and packages).
