fixed some autoload issues

- calendar should start with correctly marked entries
- org-tags-view should now recognize org-mode files correctly
implemented parametric org-journal-file-pattern

The file pattern now contains capture groups for year, month and day.
This capture group is then used to parse the file names for calendar highlighting.
auto-generate file pattern

No need to specify the org-journal-file-pattern any more. It is now
dynamically generated from org-journal-file-format.

This should simplify the setup of org-journal significantly.
minor bug fix

auto-mode-alist should work correctly, now.