Adds bit reverse function in "calculate" menu.
Adds little endian display format; 'e' button changes display to little endian and 'e' button becomes 'E' button which changes the endianness back.
1.) hitting return on the input field with the default (Enter value here) gives a random (?) value
2.) hitting return on the input field with the default should clear it
add this to input_cb():
if (strcmp(input_string, INPUT_PROMPT) == 0) {
bha->input->value("");
l = 0ULL;
}.
