Read headers with multi-line namelists

[cchall]

Headers with multi-line namelists, for example:

&description
        text="Statistics data 'opal_statfile.in' 30/12/2024 19:36:53",
        contents="stat parameters"
&end

fail to be read because tokenize_namelist returns tags and keys containing newline characters.
A simple solution is just to strip the tags and keys as they are found.

An SDDS file generated by OPAL, which has this issue, is included in test resources.

[nikitakuklev]

Another weird file to add to the collection! Thanks for the PR