Wiki anchors generated heading id

[cboos]

e.g. ChangeLog#a0.10b1

The anchor stops again at the first dot.

See:

• r3335 which removed "." from the generated ids
• r3407 which re-allowed "." in generated ids on purpose but also "swallowed" ending dots,
• r3573 which fixed the trailing dot case in a too expeditive way...

Time to write good unit tests for this, I guess.

[cboos]

Fixed by r3718.