Makefile tweaks. (#376) ...

-Have fusee-secondary clean sept-secondary as required.
-Use $(TARGET) variable for sept-secondary, and clean the encrypted output as required.

Fix sept-secondary build when using prebuild sept-secondary.enc (#371)

Allow the user to build with a prebuilt sept-secondary blob via a SEPT_ENC_PATH variable. (#365)

sept: prepare for reboot immediately

sept_sign: Python 3 compat (#356)

sept-sign: uncorrect misguided meme correction

sept-secondary: Better meme compliance

sept-secondary: Better meme compliance

if you edit splash in a forest and nobody is around does it make a sound

fix splash boundaries

sept-s: revise splash for roundedness one more time

Sept: improve edge case cleanup a little.

sept-s: revise splash (larger, square)

sept: change splash to fancy one by @xamanthas

sept-s: turn on backlight after drawing image.

Fix copy/pasted copyright notice

sept-s: splash! (thanks @CtCaer, @balika011)

sept-s: redefine a while.

sept-s: fix building without keys (output won't work though)

sept-s: First functional version.

sept-s: Implement key derivation

sept-s: remove a bunch of debug garbage

sept-secondary: reboot to clean state + grab keys from SE

sept: implement cryptographic meme

sept: add secondary skeleton + buildscript

sept: commit working primary.