Section numbering characters bear source information

[ktraunmueller]

The char nodes emitted for section numbers may somehow have source information attached. In the following example, the dot in "1.1" on page 2 has source position of the "Introduction" section on page 1:

Steps to reproduce:

• Start typing on page 1.
• At some point, page 2 will become selected, because the section number from page 2 suddenly has source position from page 1.

Document to reproduce the issue

[ktraunmueller]

Fixed in 1.3

[ktraunmueller]

Reopening, still happens with the attached document:

Umlaute.tex.zip

[ktraunmueller]

Duplicate of #564