Filtered flat import of Oliver's svn package management branch

Bring the changes that aren't package management related and the ones
that are but don't take effect as long as they are ignored by the build
system into the master.

Summary of changes:
* Introduce private header <directories.h> with constants for a good
  deal of paths that should usually be retrieved via find_directory().
* Replace hard-coded paths by using find_directory() or the
  <directories.h> constants (e.g. in drivers and the kernel).
* Add find_directory() constants needed for package management.
* Add __HAIKU_ABI_NAME and B_HAIKU_ABI_NAME macros.
* src/apps/deskbar: BeMenu.* -> DeskbarMenu.*,
  DeskBarUtils.* -> DeskbarUtils.*
* Change deskbar menu settings directory from ~/config/be to
  ~/config/settings/deskbar.
* Other smaller cleanups, changes, and fixes.

headers/config/HaikuConfig.h

@@ -9,6 +9,7 @@
 /* Determine the architecture and define macros for some fundamental
    properties:
    __HAIKU_ARCH					- short name of the architecture (used in paths)
+   __HAIKU_ARCH_ABI				- name of ABI (as in package architecture)
    __HAIKU_ARCH_<arch>			- defined to 1 for the respective architecture
    __HAIKU_ARCH_BITS			- defined to 32/64 on 32/64 bit architectures
    								  (defaults to 32)
@@ -19,25 +20,35 @@
 */
 #ifdef __INTEL__
 #	define __HAIKU_ARCH					x86
+#	if __GNUC__ == 2
+#		define __HAIKU_ARCH_ABI			"x86_gcc2"
+#	else
+#		define __HAIKU_ARCH_ABI			"x86"
+#	endif
 #	define __HAIKU_ARCH_X86				1
 #	define __HAIKU_ARCH_PHYSICAL_BITS	64
 #elif __x86_64__
 #	define __HAIKU_ARCH					x86_64
+#	define __HAIKU_ARCH_ABI				"x86_64"
 #	define __HAIKU_ARCH_X86_64			1
 #	define __HAIKU_ARCH_BITS			64
 #elif __POWERPC__
 #	define __HAIKU_ARCH					ppc
+#	define __HAIKU_ARCH_ABI				"ppc"
 #	define __HAIKU_ARCH_PPC				1
 #	define __HAIKU_BIG_ENDIAN			1
 #elif __M68K__
 #	define __HAIKU_ARCH					m68k
+#	define __HAIKU_ARCH_ABI				"m68k"
 #	define __HAIKU_ARCH_M68K			1
 #	define __HAIKU_BIG_ENDIAN			1
 #elif __MIPSEL__
 #	define __HAIKU_ARCH					mipsel
+#	define __HAIKU_ARCH_ABI				"mipsel"
 #	define __HAIKU_ARCH_MIPSEL			1
 #elif __ARM__
 #	define __HAIKU_ARCH					arm
+#	define __HAIKU_ARCH_ABI				"arm"
 #	define __HAIKU_ARCH_ARM				1
 #else
 #	error Unsupported architecture!