On-board 4MB SPI flash

[ScruffR]

There has been an update post on the improved QSPI flash and yes it is supposed to be accessible.

@will

Upgraded flash memory
We upgraded the flash memory available on each Particle Mesh device by adding a whopping 4MB of external flash which can be used for data logging, firmware backups, and future feature development. The flash is QSPI compatible and supports XIP (execution in place), enabling you to run executable code from external flash in addition to simply reading and writing to memory.

I think the APIs to write to these areas aren't finalised yet, but reading should be transparent - if I'm not mistaken.