Spirit:  Restore the 96 byte maximum packet length.  Reducing the packet length had no effect on eliminating RX FIFO errors.

Spirit Network Driver:  Add support for watermark interrupts on RX FIFO.  Reduce max packet length to avoid an errata.

IEEE 802.15.4 network drivr:  Fix more compile issues that only show up when CONFIG_NET_STARPOINT is defined.

IEEE 802.15.4 network driver:  Fix some errors introduced in previous commit.  Clean up some of the casting logic.

Spirit + 6LoWPAN:  In STAR configuration, Spirit must use a configured well known hub address.  6LoWPAN cannot assume that the PAN coordinator is the STAR hub; it must ask the radio to provide it with the address of the star hub

B-L475E-IOT01A: Make spirit-6lowpan configuration match what is currently under test:  Enable multicast, broadcast, but disable CRC support.  Currently CRCs are not working right.

Spirit: Increase number of retries if there is no acknowledgement; Add interrupt handling for the case where the max number of retries expires.  Fix some badly implemented queue management code.  With these changes the basic UDP and TCP tests work.

Spirit:  Convert network driver to use STack packets vs. Basic packets.  We need to use the STack packets in order to provide the source address.

Spirit: Correct setting of the length width field; Add multicast and broadcast addresses to radio properities.

Spirit network driver:  Need to enable sending of TX address.  Moved some non-optional settings out of board.h to driver.

RAMTRON:  Should be able to select chunked write mode via a configuration option, not by editing the file.

RAMTRON: Add support for splitting block writes in chunks.  Some Re-RAMs like MB85AS4MT has a write buffer size limitation.

drivers: handle I2C_TRANSFER return value consistently.  Some I2C peripherals transfers return zero on success, others number of completed transfers. Make drivers robust against this.

spirit:  Modify reg needs to toggle CS to get the correct status.  Remove some delbug left in last commit.  make sprit_unlock an inline function.

poll: fix poll for regular files and block devices.  Open Group documentation tells that poll (and select) support regular files and that 'Regular files shall always poll TRUE for reading and writing'.

Spirit: Fix typos in conditional compilation. Add debug output.  Remove extra clear of pending interrupts, could cause missing interrupts.  Add spirit_reg_modify() which is not currently used.

Spirit Network Device:  Fix a deadlock.  Also several other design improvements to eliminate corner cases.

Fix for stm32f746g-disco board for button support with interrupt. This change is tested with buttons app example and it is working with interrupts (signals). I tried the test with polling but at this point it doesn't work.