Add `T` or `t` shortcut

[markets]

Introduce a global method T (or t) as a shortcut for convenience:

>> T(:hello)
=> "Hello"

Let's say T (or t) should be the same as MiniI18n.t. Probably, introduce also L (or l) to quickly call MiniI18n.l.

In terms of implementation, probably the way to go is to just inject those methods in the Kernel module.