- Simplify doctests for periodexpr.
- Besides consuming leading space consume ending space for periodexpr also.
- Drop implicit option (def, def) behaviour of periodexpr. I.e. disallow
hledger reg -p '' and auto-transaction with heading just '~'.
- Slightly re-factor periodexpr.
- Ensure that reportinginterval doesn't consume trailing space.
Useful if we'll start disallowing periods like "every1stjan2009-".