[BUGFIX] fix ter upload

* make sure source path has a trailing "/"

related to #1
[BUGFIX] avoid PHP notice on "Undefined index: constraints"
[FEATURE] extract: create dest path if not exists
[FEATURE] extract: confirmation message
[BUGFIX] extract: do not abort on empty files
[TASK] extract: make sure destination path has a trailing "/"
[TASK] extract: check if t3x file is readable
[FEATURE] create t3x file from ext directory
[TASK] update phar