Support .navigation+.lst (see ) and .navigation+.turf (see ) definition files. These files will add to existing navigation, cumulatively, up the hierarchy from the last defined navigation.
In other words, for any page the .navigation.* definition file at the highest level below the page "resets" the navigation. Starting at that level upwards to and including the level of the page, any encountered .navigation+.* (note the plus sign) will cumulatively add to the navigation.
As a practical matter, to make this ticket easier to implement quickly, this implementation will have two limitations:
.navigation+.* files will only take effect if there is a .navigation.* definition up the hierarchy. If navigation is being auto-determined, then any .navigation+.* files will be ignored.
No merging will take place. Any additive navigation definitions will simply be placed after existing (already-determined) navigation definitions.
Hmmm… this works for all the pages in a directory, but it doesn't help if a single page needs to expand the available navigation. I'll have to do more thinking on that.