Use unsigned types for bit manipulation

Reason

Unsigned types support bit manipulation without surprises from sign bits.

Example

unsigned char x = 0b1010'1010;
unsigned char y = ~x;   // y == 0b0101'0101;

Note

Unsigned types can also be useful for modular arithmetic. However, if you want modular arithmetic add comments as necessary noting the reliance on wraparound behavior, as such code can be surprising for many programmers.

Enforcement

• Just about impossible in general because of the use of unsigned subscripts in the standard library
• ???