We removed the boost headers in issue617.

Sounds good! If it helps, I also volunteer to contribute to replacements for
boost::any and/or boost::dynamic_bitset. Sounds like a fun self-contained
programming task. :-)

But I'm not sure how soon I could do this, so feel free to ignore this or come
back to the offer at a later time.

We discussed this and came up with the following suggestion.

Jendrik will try to avoid the boost dependency in issue600 and I will try to
remove the dependency on boost::any in issue617.

If we both succeed, we can close this issue as obsolete.

If Jendrik succeeds and I can't find a good alternative for "any", we could
still update the existing files of boost to a more up-to-date version, which
would avoid annoying warnings on Windows.

If it turns out that we need boost's bitset for efficient CEGAR code, we'll
discuss our options again.

Better, but I'd still be somewhat reluctant to pay that price if it's only a
temporary addition anyway and we're planning to remove the dynamic_bitset code
from ext soon anyway.

We could also use boost-1.54 (the boost version of Ubuntu 14.04) which "only"
adds 2.5 MB.

If we ever get around to creating the slimmer repository we were planning to
create, perhaps it would be a bad idea to add the rather large dynamic_bitset
headers. Once added, they remain in the history forever unless we strip the
history again, and I think we shouldn't plan to add things that we would later
strip.

Some size considerations. Currently, I get the following sizes for the working
directory of a fresh clone:

331.7 MB benchmarks
  6.0 MB src
  1.9 MB experiments
  0.4 MB misc
  0.1 MB driver

We can split up the src directory further:
  3.5 MB search
  1.8 MB VAL
  0.6 MB translate
  0.1 MB preprocess
 <0.1 MB cmake_modules

And splitting up src/search further:
  1.4 MB ext
  2.1 MB (everything else)

If we remove the benchmarks and VAL, we end up with working directory size of
6.6 MB. If we additionally remove ext, we end up with a size of 5.2 MB.

If we add the new boost code to this, we have 16.2 MB, i.e., the size triples
because of boost. This is perhaps a bit much.

Remove all current Boost files then add all Boost version 1.60 headers required 
by any.hpp or dynamic_bitset.hpp.