Use PHP shortcuts
Changes in date handling

- Show dates properly in solution form (with leading zero).
- No default date in publishing form.
Scale textareas only vertically
Adapt .gitignore to new directory structure
Use the environment variable PBROOT everywhere

It was only used partially before. That was nonsense.
To be seen as amendment to c9e00edb504ccd041ada2ec884a0c34e1cbfe073.
Use only one env variable to store database credentials