Macros for container literals with specific type.
```
#[macro_use] extern crate maplit;
# fn main() {
let map = hashmap!{
"a" => 1,
"b" => 2,
};
# }
```
The **maplit** crate uses `=>` syntax to separate the key and value for the
mapping macros. (It was not possible to use `:` as separator due to syntactic
restrictions in regular `macro_rules!` macros.)
Note that rust macros are flexible in which brackets you use for the invocation.
You can use them as `hashmap!{}` or `hashmap![]` or `hashmap!()`.
Generic container macros already exist elsewhere, so those are not provided
here at the moment.