sw: add irq flags save/restore functions

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: fix eeprom write, add eeprom read

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: add pending IRQ flags

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: add keys IRQ handling

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: rearrange initialization sequence

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: display current temperature on LCD

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>