Implement fault-injection resistant patterns

[henopied]

• [x] Random delay at the start of each transaction (and in between)
• [x] Multiple conditional checks for security-critical operations (e.g. three if-statements, multiple runs of password hash verification function, fail default)
• [ ] TRNG entropy test (ensure that bytes are constantly changing, look into a formal method)
• [x] #63
• [ ] Use internal and external clocks to determine if overclocking is occurring
• [x] #64
• [ ] I2C interrupt when AP loses master arbitration - defend by pulling down SCL
• [x] Prevent recovery from panic with inline ASM at the bottom of the panic handler