Implemented avl_alloc()
Merge pull request #64 from matthiasbeyer/implement-avl_alloc

Implemented avl_alloc()
Implemented avl_destroy()
Merge pull request #65 from matthiasbeyer/implement-avl_destroy

Implemented avl_destroy()
Add script for style checking
Ignore Testing subdirectories brought up by ctest
Have the path of the style checking script
Add variable holding all header files
Add style check each header and source file
Enable testing
Install astyle on testing VM
Run ctest as part of Travis CI tests