overhaul features checklist

[ExpandingMan]

• Both more robust and more flexible file management. Users should have the ability to name files easily but also forget about underlying file management if they want to.
• DataStreams integration and arbitrary output types for files. Should completely drop DataFrames as a dependency.
• Both more robust and more flexible approximation schemes for memoizing numerical output.
• More flexibility in how function calls appear. The MacroTools integration will solve this easily.