Reintroduce binary to load and save dill file.

Reintroduce binary to load and save dill file.

The kernel_binary file as code for write as well as for read.
Previously we had a binary that could load and save the dill
file so we could check that the writing at least produced
a valid output (by roundtripping).
This reintroduces that binary, as well as fixes the writing
to actually allow for roundtripping.

[jensj, 2017-01-12 10:04:10]

jensj@google.com changed reviewers:
+ kustermann@google.com

[jensj, 2017-01-12 10:04:10]

a) Whether we actually still want this or not, I'm not sure (but if we don't,
shouldn't we get rid of the writing code?)

b) this is mostly copy-paste from different sources (main.cc, the old version
doing this etc).

c) I have no idea what I'm doing in regards to the gn file --- again I've
copy/pasted and it seems to work...

[jensj, 2017-01-12 11:11:01]

Closing this as consensus seems to be that we should delete the writing code
instead.