[Dune] how to transpose a matrix

[Aleksejs Fomins]

Dear Dune,

I am sorry for a very trivial question, but how does one transpose an
existing matrix (i.e. DynamicMatrix). I am unable to find the
corresponding method in the documentation.

I mean, I can write it myself and it will be 2 lines of code, but I am
sure I am just blind :)

Greetings,
Aleksejs