Various Cleanups

The changes in this pull request only touch files that were added in this LSP fork.

* Format sources (clang-format)
* Follow LLVM coding standards (preincrement, no "using namespace std;")
* Use some new C++11 features like nullptr, override modifier (clang-modernize)
* Use range-based for loops
* Add static modifier to command-line option definitions
* Some simplifications