Use explicitly sized types from stdint

Replace bare int types with stdint types. This was done with:

    grep -rwl 'int' src/ | xargs sed -i 's/\<int\>/int16_t/g'
    grep -rwl 'unsigned long' src/ | xargs sed -i 's/\<unsigned long\>/uint32_t/g'
    grep -rwl 'unsigned char' src/ | xargs sed -i 's/\<unsigned char\>/uint8_t/g'

Then reverted for *main(), putchar(), and getchar().

The Arduino declarations for parallel_main() were also corrected to
match their definitions.

SDCC does *not* generate the same code in all instances, due to `int`
being treated different than `short int`.

Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/board/arduino/uno/i2c.c

@@ -5,7 +5,7 @@
 #include <board/cpu.h>
 #include <board/i2c.h>
 
-void i2c_init(unsigned long baud) {
+void i2c_init(uint32_t baud) {
     TWAR = 0;
     TWBR = (uint8_t)(((F_CPU / baud) - 16 ) / 2);
     TWCR = 0;