Description and GUI for EPA files

[ChristopherRabotin]

High level description

Loading an EPA file in the GUI shows ... nothing. Similarly, there is no information when calling describe() on an Almanac which only contains an EPA file. This makes it in practice impossible to see what we've loaded.

Requirements

• Add a description of loaded EPA files
• Add a GUI render of EPA files

Test plans

Check that describe shows something useful.