Revision 838

Big revision of the FLASH infrastructure so it's easier to
integrate FLASH write drivers into the system.  For OLPC,
there is no functional difference at the top level, but
the internal arrangement of the FLASH device node subtree
has changed.  It's now possible to compile an OLPC ROM
that can save configuration variables in an SPI FLASH
block (see config.fth:use-flash-nvram).  For the lxdevel
build, that option is now chosen by default.