add data.text to benchmarks
add basic datatype refinements and comment out stuff that was making
us crash
add embeds for Data.Word
add embed for Int64
yikes, merge conflict from a stash pop..
the Read Text instance was infecting the environment with a Bot and
preventing any useful checks..
add type for init
add refinements for append, head, last, tail, init, and length
add a bunch of length-related refinements to Data.Text, all currently broken
add refinements for stream functions to track length
take should talk about the number of chars in the Text,
not the tlen (number of bytes).

still need to convince liquid that (numchars _ _ 0 == 0), and
hopefully clean up the annotations...
add axiom_numchars to inject (numchars _ _ 0 = 0)
temporarily comment annotations for take and drop.

add annotations for many others
add annotations for many more functions, and a few comments where we
should be able to say something interesting
add Text.jhala.hs
fix Data.Text.take

needed to add numchars refinements for the `n <= 0` and `n >= len`
branches. introduced `axiom_numchars_length` for the latter.
use invariants instead of axioms for numchars

seems to help a lot with performance