* Write some of the basic infrastructure for SRAM support.
* Implement battery-backed SRAM.
* Implement non-Atmel Flash chips.
* Implement support for Atmel Flash SRAM chips.
* Implement EEPROM support, various refactorings to SRAM system.
* Replace Save API with one based more cleanly on the flash chip API.
* Run rustfmt on new save media code.
* Improve test_savegame and fix remaining bugs caught by the changes.
* Proofreading on comments/documentation for save module.
* Fix addresses for read/verify routines in save::flash.
* Rebase save_api onto current master.
