Fix incompatibility with Twig v1.33.2
Fix incompatibility with Twig v1.33.2

Instantiation of Twig_Loader_Filesystem was failing on second parameter, which is expected to be a string variable representing file path common to path passed in first parameter, not a setting array as is passed in current version of this class in master.  I did not check impact on other areas of code (i.e. impact of removing cache/debug settings), but simply removing this parameter allow markdown generation to work in my environment.
evert/phpdoc-md,evert/phpdoc-md