Operation Inlining

[bettinaheim]

We gradually want to incorporate some of the compilation steps and optimizations usually done for classical programming languages (opposed to quantum programming languages) into the Q# compiler. While our focus is naturally on different aspects of a program when compiling and optimizing for execution on a quantum processor, we still need some of the classical infrastructure as well.
In particular, we want some infrastructure for inlining operations.

[bettinaheim]

Since this task is part of a larger piece containing the first steps to set up some infrastructure for a full compilation process, I set up a feature branch to PR again here: https://github.com/microsoft/qsharp-compiler/tree/features/classicalCompilerOptimizations
Such a feature branch may contain parts of a task and/or experimental implementations with the intent to eventually merge it back to master once it is in a reasonably good state.

[bettinaheim]

Merged into master with #177