Allow colons in bracket parameter syntax

[brjann]

Reitit allows two syntaxes for path parameters, colon and bracket syntax

[["/users/:user-id" {:handler get-user}]
 ["/api/:version/ping" {:handler ping-version}]]
[["/users/{user-id}" {:handler get-user}]
 ["/files/file-{number}.pdf" {:handler get-pdf}]]

The bracket syntax is required for namespaced keywords, for example

[["/users/{user/id}" {:handler get-user}]
 ["/files/file-{file/number}.pdf" {:handler get-pdf}]]

However, when using the bracket syntax, you lose the correspondence between keywords in the route and keywords in the request map. I think it would be very helpful if also the bracket syntax would allow a colon, i.e.,

[["/users/{:user/id}" {:handler get-user}]
 ["/files/file-{:file/number}.pdf" {:handler get-pdf}]]

This gives you immediate visual recognition of keywords in the route.

[opqdonut]

This would improve greppability of code, I like the idea. PR welcome!