Intelephense loads only its 68 default stub sets, so code using redis,
imagick, memcached, wordpress and the like showed "Undefined type", and
there was no way to point it at a platform's classes outside the project.
- Each ext-* in require or require-dev of the root composer.json adds its
stub set, and Settings › PHP › Additional stubs adds others (wordpress).
`stubs` replaces Intelephense's defaults, so the defaults are sent with
the additions; nothing is sent when nothing is added.
- Settings › PHP › Include paths: folders (absolute, ~/ or relative to the
project) sent as environment.includePaths.
Both apply on composer.json and settings changes without reopening the
project; Settings › Language Servers options still win.
Fixes#1232Fixes#1233