Unexpected behaviour of print(char, HEX) and print(int, HEX)

```
char c = 255;
Serial.print(c, HEX);
```

produces

```
FFFFFFFF
```

This is due to the fact that `print(char c, int base)` convert char c (1 byte) into an unsigned long (4 bytes). As char is signed 255 is in fact -1(Two's complement), once written in 4 bytes it becomes FFFFFFFF. But as a user I would rather have FF than FFFFFFFF.

The problem exist with int (2 bytes) too

Here is a more complete example:

```
void setup() {
Serial.begin(9600);
int i = 1;
Serial.print("i: ");
Serial.print(i, 10);
Serial.print(" | ");
Serial.println(i, HEX);
i = -1;
Serial.print("i: ");
Serial.print(i, 10);
Serial.print(" | ");
Serial.println(i, HEX);

char c = 127;
Serial.print("c: ");
Serial.print(c, 10);
Serial.print(" | ");
Serial.println(c, HEX);
c = 255;
Serial.print("c: ");
Serial.print(c, 10);
Serial.print(" | ");
Serial.println(c, HEX);
}

void loop() {}
```

output

```
i: 1 | 1
i: -1 | FFFFFFFF
c: 127 | 7F
c: -1 | FFFFFFFF
```

where I owuld rather have

```
i: 1 | 1
i: -1 | FFFF
c: 127 | 7F
c: -1 | FF
```

Start by locating the Serial.print(char c, int base) and Serial.print(int, int base) overloads described in the issue, then run the complete example sketch to reproduce the output. Done means hexadecimal output uses the operand's width, producing FFFF for -1 as an int and FF for -1 as a char, while preserving the existing decimal output.

Written by the indexing model from the issue text.