Instead of actually defining each unused handler as an individual
"function" with an infinite loop, make them all reference the default
handler.  This shaves 192 bytes of unnecessary bloat off the .text
section.

Currently, misbehaving l0dables which trigger some kind of CPU exception
will busy-spin in the exception handler with no way to return to another
app without a full reboot.

Fix this by calling epic_exit() in case of an exception to hopefully
allow a return to menu in most situations.

After main() returns, don't enter a busy loop but call epic_exit() to
signal to epicardium that the l0dable has finished.  The exit code will
be the return value from main().

Signed-off-by: Rahix <rahix@rahix.de>

Add blitting function to display

See merge request !349

change(bsec): Update documentation

See merge request !444

See merge request !443

change(main): rc3 splash

See merge request !442

fix(menu): Turn on MSC when no apps available

See merge request !440

feat(main): Show git info as overlay

See merge request !441

feat(ptt): Add demo app

See merge request !439

feat(hid-demo): Allow keeping buttons pressed

See merge request !438

feat(bsec): Add to BME680 demo

See merge request !435

Basic PTT implementation

See merge request !436

change(ble): Remove unused battery service

See merge request !437

It was never properly implemented and only leads to confusion.

BSEC support

See merge request !380