Cleaner C Interface (v0.9.1)

This release merges the c_adapter into the jluna shared library. jluna::initializes signature was modified. It is now:

 void initialize(
      size_t n_threads,    // number of threads to initialize julia with, default: 1
      bool suppress_log, // should logging be disabled, default: false
      const std::string& jluna_shared_library_path, // path to libjluna.so, or "" to use default path
      const std::string& julia_image_path                // path to julia image, or "" to use default image
  )

Please make sure to delete any old libjluna_c_adapter.so:

cd <path to shared library install directory>
rm libjluna_c_adapter.so # pre- and suffix are platform dependent

Then do a fresh compile:

# in jluna directory
cd jluna
rm -r build
mkdir build
cd build
cmake .. -DJULIA_BINDIR=$(julia -e "println(Sys.BINDIR)")
make install

Other than this, only the documentation was updated to reflect these changes.