remove deprecated use of `std::str::from_char`
remove deprecated use of `std::slice::ImmutableSlice::shift_ref`
remove deprecated use of `std::collections::hashmap::HashMap::get`
change `parser::Attr` from enum to struct
replace uses of `move_iter` with `into_iter` and `mut_iter` with `iter_mut`
Merge pull request #7 from apasel422/fix-warnings

Update code for rust master