Split commands internally into logic and presentation

[Zirak]

Point 2 in Roadmap/Innards: Commands have mixed logic and presentation. Notably:

• [x] parse
• [x] eval
• [ ] stat
• [ ] history
• [ ] urban
• [ ] weather
• [ ] wiki

The fix should be relatively easy, and it'll fix some problems - especially in the /learn -> /parse bridge. Man that one sucks.