I was having issues with the bus freezing up .. slaves holding SDL low.. so I rewrote a good portion of the interrupt logic based on the application notes from Atmel.  One major improvement is using the RXNACK flag in the STATUS register, which indicates that no device responded to an address packet. Assuming that the chip will always give an interrupt status, I believe it's possible to eliminate the timer as well.

stm32f429i-disco, stm3240g-eval, stm3220g-eval, stm3210e-eval:  Eliminate duplicate Make.defs files.

Build System:  It is no longer necessary to have a unique Make.defs file for each configuration.  A board may share a common Make.defs file in the scripts directory.

ipforward.h:  Add some forward references that are needed when CONFIG_NETDEV_MULTINIC is not enabled.

Fix some errors in ipforward.h when CONFIG_NET_STATISTICS is enabled, but CONFIG_NETDEV_MULTINIC is not

tools/refresh.sh: Now runs make savedefconfig before copying the new defconfig file in place;  Also, added a new option --defaults.  Since the number of defaults that you now have to answer is so large, the option lets you just accept the default values.  So it works just like --slilent but still prompts you for the decision to save or discard the new defconfig file.

Update configure.sh, configure.bat, configure.c:  With compressed format, part of the installation requires that we run 'make olddefconfig' to restore the uncompressed defconfig format.  Also, while I was at it, I also added options to select host platform on configure command line.