[Possible PR] Fix to_hstring to stop it from using a negative index.

[Trikzon]

In cstr.cpp inside of the for loop you index your hexTo_StringOutput with a negative index when i goes past 7.

This can be fixed like so:

char hexTo_StringOutput[128];
const char* to_hstring(uint64_t value){
    uint64_t* valPtr = &value;
    uint8_t* ptr;
    uint8_t tmp;
    uint8_t size = 8 * 2 - 1;
-   for (uint8_t i = 0; i < size; i++){
+   for (uint8_t i = 0; i < size / 2 + 1; i++){
        ptr = ((uint8_t*)valPtr + i);
        tmp = ((*ptr & 0xF0) >> 4);
        hexTo_StringOutput[size - (i * 2 + 1)] = tmp + (tmp > 9 ? 55 : '0');
        tmp = ((*ptr & 0x0F));
        hexTo_StringOutput[size - (i * 2)] = tmp + (tmp > 9 ? 55 : '0');
    }
    hexTo_StringOutput[size + 1] = 0;
    return hexTo_StringOutput;
}

I am willing to pr this change if you want, but I'm not sure if you want it to be pulled into all branches since episode 4 or not.