Hooks

- Supports 'debug.hooks' configuration setting.
Config

- Removed obsolete (or rather, unused) 'extensions' variable.
Documentation

- Removed 'extensions' mention, and improved 'debug.tls' section.
Util

- Minor formatting.
Documentation

- Added not about debug value propagation.
Context

- Corrected comment.
Filter

- Modified diagnostics to observe rc.debug.parser.
Parser

- Modified to obey rc.debug.parser.
Documentation

- Added rc.debug.parser.
Task

- Upgrades legacy recur values.