Manage element attribute syntax for textual planes selection in XTZ import parameters

See first item of “Syntaxes de sélection supplémentaires” list in “Étape 3 : TXM 0.8+” section in https://groupes.renater.fr/wiki/txm-info/public/import\\\_xtz#plans_textuels.

Example usages

• paginate with only the 'editionname' pb with "pb@head=editionname"
• create lines with only the 'editionname' lb with "lb@head=editionname"
• [SLH]
  • put on out-of-text-to-edit all speech turns by LOC1 : sp@who="LOC1"
  • put on out-of-text all spans of type 'comment' : span@type="comment"
  • put on out-of-text-to-edit all heads of figures : figure/head

Priorities of development

1. all elements X with attribute Y (most usefull)
2. all elements X with attribute Y at value Z (usefull)
3. all elements with attribute Y at value Z (usefull)
4. all elements X with attribute Y not at value Z (usefull)
5. all elements with attribute Y not at value Z (usefull)
6. all child elements X of element Y (e.g. figure/head) (usefull)
7. all elements X with attribute Y at value Z and with attribute T at value U (bonus)
8. all child elements X of element Y with attribute Z at value T
9. all child elements X with attribute Y at value Z of element T

Solutions

• Create a micro syntax (like URSQL) to better target the XML elements of textual plans
• Use CSS elements+attributes selectors syntax https://www.w3schools.com/cssref/css_selectors.asp

(from redmine: issue id 2383, created on 2018/05/25 by Matthieu Decorde)