Update "themeinfo" for Moodle 2.6 to use core_useragent.

When using "theme-info" in Moodle 2.6 I got the following error message (2 messages combined into one sentence)

Error message: "get_device_cfg_var_name" || "get_device_type_list" has been deprecated, please update your code to use core_useragent instead.

To solve the issue I did the following:
Copy the ThemeInfo command to the 2.6 commands, change the namespace "Moosh\Command\Moodle26\Theme" and implement the \core_useragent calls.

You may be interested in the changes and have a look at the solution.