Merge with C Expr Eval

[lks9]

The PR on angr was rejected but we need it here. So the idea is to just merge it in this project.

[lks9]

I see two problems for the future here:

1) The small pieces in the examples folder work with debugging info. But for some reason, the debugging info on the larger binary (busybox) was not loaded at all. 2) Debugging info is only useful when the binary is compiled with optimization turned off. But we need the same instrumentation for tracing and retracing. This does not seem to be a problem first: Since instrumentation is done to the pre-processed files, we need the same pre-processor options for tracing and retracing. Afterwards, we can compile the optimized tracing version with -O3 and the unoptimized retracing version with -O0. In reality, however, I got compiler errors when trying to compile the unoptimized retracing version from an optimized pre-processor output.

So I gave up on that issue and decided to work on an alternative way to solve the assertion issue three weeks ago: 0195bcd658cb3a651d1fd571e57dd5a281a1750a