lints: Add extra clippy lints used at Traverse

These are the extra lints that we have enabled over at [Traverse]. They
were mostly picked at random a while back by looking at default-allowed
lints and is likely incomplete. In addition we have these pending,
hoping they become useful one day after fixing all violations:

    clippy::clone_on_ref_ptr
    clippy::cognitive_complexity
    clippy::pattern_type_mismatch
    clippy::unimplemented
    clippy::use_self

[Traverse]: https://github.com/Traverse-Research/

lints.rs

@@ -13,36 +13,44 @@
     clippy::exit,
     clippy::explicit_into_iter_loop,
     clippy::filter_map_next,
+    clippy::float_cmp_const,
     clippy::fn_params_excessive_bools,
+    clippy::get_unwrap,
     clippy::if_let_mutex,
     clippy::imprecise_flops,
     clippy::inefficient_to_string,
     clippy::let_unit_value,
     clippy::linkedlist,
     clippy::lossy_float_literal,
     clippy::macro_use_imports,
+    clippy::map_err_ignore,
     clippy::map_flatten,
     clippy::map_unwrap_or,
     clippy::match_on_vec_items,
     clippy::match_wildcard_for_single_variants,
     clippy::mem_forget,
     clippy::mismatched_target_os,
+    clippy::mutex_integer,
     clippy::needless_borrow,
     clippy::needless_continue,
     clippy::option_option,
+    clippy::print_stdout,
     clippy::pub_enum_variant_names,
     clippy::ref_option_ref,
     clippy::rest_pat_in_fully_bound_structs,
+    clippy::string_add,
     clippy::string_to_string,
     clippy::suboptimal_flops,
     clippy::todo,
+    clippy::trivially_copy_pass_by_ref,
     clippy::unnested_or_patterns,
     clippy::unused_self,
+    clippy::useless_transmute,
     clippy::verbose_file_reads,
     future_incompatible,
     nonstandard_style,
     rust_2018_idioms
 )]
 // END - Embark standard lints v0.2
 // crate-specific exceptions:
-#![allow()]
+#![allow()]