Use selected() in touch_time(), page_template_dropdown(), parent_dropdown(), and add head docs

[meloniq]

Use selected() in touch_time(), page_template_dropdown(), parent_dropdown(), and add head docs.

Suggested by @SergeyBiryukov in #25879 to separate this changes from adding filter hook.

The touch_time() function probably could be described better.

[meloniq]

use selected(), add head docs

[matt]

Hasn't been much activity here, let's look at it for after the 3.8 release.

[DrewAPicture]

Standardized docs

[DrewAPicture]

25889.2.patch​ brings the inline docs in-line with the ​standards

[wonderboymusic]

In 27188:

Use selected() where appropriate in touch_time(), page_template_dropdown(), and parent_dropdown(). Also, add proper docs.

Props meloniq, DrewAPicture.
Fixes #25889.

[TobiasBg]

@wonderboymusic: Seems like you (accidentally?) added get_the_permalink() for #24164 in [27188]?
Well, as the discussion in #24164 agrees, closing that as fixed with [27188] should also be ok.

[wonderboymusic]

EEK. Removed in [27189].