Use "make" function for sfnt instead of classes.

I’ve been spoiled by immutable data structures. The mutability of
prototypes causes weird errors that I’ll try to avoid by initializing
structures through pure functions.
Use "make" functions for all other tables.
Use correct length for LONGDATETIME.
Add LITERAL encoding.
Simpler table encoding.
Name table uses correct types.
Fix DICT encoding.
Avoid encoding bytes twice to download font.
Write out private dict and local subroutines.