Fix warning about redundant patterns

/Users/ilya/Code/rust/zinc/src/ioreg/builder/utils.rs:95:23: 95:45 warning: the `opt_name:` in this pattern is redundant and can be removed, #[warn(non_shorthand_field_patterns)] on by default
/Users/ilya/Code/rust/zinc/src/ioreg/builder/utils.rs:95     node::EnumField { opt_name: ref opt_name, ..} => {
                                                                               ^~~~~~~~~~~~~~~~~~~~~~
/Users/ilya/Code/rust/zinc/src/ioreg/builder/register.rs:63:23: 63:45 warning: the `variants:` in this pattern is redundant and can be removed, #[warn(non_shorthand_field_patterns)] on by default
/Users/ilya/Code/rust/zinc/src/ioreg/builder/register.rs:63     node::EnumField { variants: ref variants, .. } => {
                                                                                  ^~~~~~~~~~~~~~~~~~~~~~
Cleanup unused import warning on test
Fix a few miscelaneous warnings
Merge pull request #211 from errordeveloper/master

Fix most warnings