Merge pull request #193 from TvdW/develop

Implement POSIX.1-1988 UStar directly instead of calling the tar binary
Undos integration of custom TAR creation.
Updates packaged download extension.
Correct root dir in php_tar.
Adds workaround to use direct POST-request downloads.
Write files in segments.
Semantics.
Uses EXIF-thumbs to generate thumbs if possible.
Fixes and refactoring in Image class.
Updates readme.
Removes PharData check.
Refactors php_tar. Fixes tar file header, now supports long paths. Adds support for emtpy dirs. Ignores empty files (failed).
php_tar: fixing emtpy files bug.
php_tar: Fixes total size.
Refactors php_tar.
Refactors php_tar.
Refactors php_tar.
Removes newline.
Sematincs.
Removes tiff from preview and thumbnails. Still broken.