- common.mk has been tweaked so that the OpenWrt compilation process is
more flexible: one can now choose an OPENWRT_TARGET and the
OPENWRT_ROOT instead of just the OPENWRT_VERSION.
- The OPENWRT_VERSION's default value trunk" has been removed.
- Makefile_atheros_openwrt has been deleted, since with recent OpenWrt
versions (12.09) everything should compile just fine, and we are not
specific to the atheros target any more.
- INSTALL.t2t has been updated to reflect these changes, and a new
section was added to explain how to compile your own toolchain.