Commit generated bindings to repo

We would like to make the Python UX as easy as possible. One issue we will have is with pyQuil: we want uses to be able to use pyQuil with or without libquil available. If libquil is installed on their system and they want to use it -- awesome. But if libquil is not available on their system, they should still be able to pip install pyquil without issue.

The problem arises in this situation:

• user runs pip install pyquil
• pyquil depends on qcs-sdk-python
• qcs-sdk-python will need to be compiled with libquil support (as there is no way to configure this with the Python package system)
• qcs-sdk-python will look for libquil.h in order to generate its bindings

If the user has not installed libquil, the final step will fail.

One way I see around this is to remove the need to generate the bindings at compile time, by having them stored in the libquil-sys repo. We have done this in other projects: in build.rs support a feature flag which turns on the binding generator if they need to be regenerated. Otherwise, the bindings are loading from the repo (with include_file!()).

Start in build.rs and inspect how libquil.h is currently used to generate bindings. Then review the libquil-sys repository for the existing include_file!() pattern and determine how a feature flag should select generated versus committed bindings. Done means pyquil can install without libquil while bindings can still be regenerated when needed.