Use byte literals in libcollections tests
Use byte literals in libserialize
Use byte literals in libdebug
Use a byte literal in libregex
Use byte literals in libterm
Use byte literal in libnum
Use byte literals in libsyntax
Use byte literals in libstd
Use byte literals in libcore
Remove cast to char in libserialize::hex
Use byte literals in libgetopts
auto merge of #16291 : nham/rust/byte_literals, r=alexcrichton

This replaces many instances chars being casted to u8 with byte literals.