chore(output): add deprecation warning and update docs

Adds a deprecation warning for use of js attribute, updates docs with an example, removes the todo for style (support for this would require additional overhead for checking proper tokenization, whether or not style properties are closed with semicolon etc)
chore(admin): Moved site secret regeneration to advanced settings.

Fixes #6443.
chore(admin): Moved site secret regeneration to the advanced settings action and form.
fix(security): Implements stronger remember me cookie strategy

This implements remember me tokens using a greater entropy pool,
replacing codes as users return to the site, and mitigating a
brute-force attack by introducing a delay when an invalid elggperm
cookie is given. For admins, the tokens are removed immediately.
Merge pull request #6524 from brettp/site_secret_18

chore(admin): Moved site secret regeneration to advanced settings.
chore(views): moved check to avoid an array index warning
chore(oauth): compatibility with OAuth PHP module
Merge pull request #6562 from sembrestels/warning-array-index

chore(views): moved check to avoid an array index warning
fix(router): better handles invalid cache requests

If a cache request doesn't match the pattern, we no longer
continue to march on into errors.

Fixes #6559
fix(menus): eliminates warnings in section menus

Handles case where $vars['items'] is empty/not an array.

Fixes #6558
Merge pull request #6567 from mrclay/6558

fix(menus): eliminates warnings in section menus
Merge pull request #6566 from mrclay/6559

fix(router): better handles invalid cache requests
Merge pull request #6565 from sembrestels/twitter-oauth

chore(oauth): compatibility with OAuth PHP module
fix(hhvm): hhvm compatibility

Reducing scrutinizer noise
fix(deprecated): fix container reference in getter function
fix(deprecated): fix incorrectly referenced variable
fix(deprecated): fix incorrectly referenced variable
fix(hhvm): hhvm compatibility

Reducing scrutinizer noise
fix(output): terminate attribute formatting early if attributes are not set

Reduce noise in logs by terminating elgg_format_attributes() early

Refs #6458
fix(views): use api to format ajax loader attributes

Reduce noise in logs by declaring variables and using elgg_format_attributes()

Refs #6458