When a Docker named volume is first mounted at /var/www/html/data,
the directory may be owned by root (the volume is created empty before
the image's chown step applies). This caused PDO::__construct to throw:
SQLSTATE[HY000][14] unable to open database file
Fix: _ensureDataDir() checks/creates the directory and attempts chmod
before every getDB() call. On subsequent calls the is_dir+is_writable
checks are O(1) stat calls with no overhead.
Fixes#34 (also closes#28#29#30#31#32#33)
dadaloop82
38c6c5aac3