The compiler gets nervous when we (for example) pass in a size_t as an int
parameter, or assign an int to a char, or assign -1 to an unsigned type. By
adding appropriate casts, we inform the compiler that, yes, we know what
we're doing.
This change also upgrades a va_arg() type from char to int, as char is
always promoted to int when passed through '...'.
String literals in C++ are implicitly typed as 'const char *', and with
this change, their const-ness is maintained when assigning them to
variables or passing them as arguments. This significantly cuts down the
number of warnings generated by the compiler.