* Changed the collected header directory (used for frameworks/libraries) to 
be a dedicated directory that uses the project name. This eliminates mixing 
collected headers and existing headers inside a Headers directory, and 
mean we won't create a Headers directory in addition the directory that uses 
the project name. OTHER_HEADER_DIRS can now be used to declare all the 
directories that contain headers. As a result, it is possible to support 
more complex projects where headers are scattered accross multiple directories 
or even subprojects with less hacks.

* Fixed LanguageKit headers to use system-wide imports. For example, 
"Runtime/LKObject.h" --> <LanguageKitRuntime/LKObject.h>

Note: the LK issue was revealed by the first change. Framework header directories 
exported in Build now match the installed framework public headers precisely. 
As a result, the build process now stops on an invalid import e.g. private 
header or subframework header referenced through a private path.


git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Languages@10455 7b3f36aa-e6db-49c1-8b4c-66eac1997e64