Allow deeply nested modules to be collapsed to a single page in rustdoc

[pcwalton]

For deeply nested module structures like those of core::libc, having to click through all the time is terribly annoying. It would be nice to have an attribute that allows all the modules to be listed on one page.

[bstrie]

From looking at the docs, it seems as though all the "nesting" modules contain nothing but other modules. Perhaps rather than an attribute we could simply have a rule that if a module's only exported items are other modules, we simply flatten it into a single page with its submodules.

[pnkfelix]

Visiting for bug triage, email 2013-07-29.

@cmr: Can this be subsumed under rustdoc_ng? (Also, is there a metabug for rustdoc_ng?)

[emberian]

@pnkfelix Yes, and no, but I'll open one: #8125

[emberian]

@pcwalton would a tree browser as in #1960 (comment) be suitable for closing this?

[catamorphism]

@cmr Any thoughts?

[emberian]

I agree that this should be done.

The best method would probably be a tree browser, ala http://docs.sencha.com/extjs/4.2.1/#!/api. Since rustdoc now handles reexports and links things properly (ex the libc doc page), I don't think this as important as it was with the old rustdoc.

[alexcrichton]

I believe that this bug is describe the quite ancient old rustdoc at this point, not the rustdoc in its current revision.

The current rustdoc I don't believe is perfect in its design, but it doesn't suffer from this same problem the old rustdoc did. In lieu of closing old and crufty issues, I'm going to close this and leave room for a more specific bug targeted at today's rustdoc design.