This replaces all of the Apache blurbs at the start of each file with an
`# SPDX-License-Identifier: Apache-2.0` string. It also fixes existing
uses to be consistent in capitalization, and to be placed above any
copyright notices.
This removes nearly 3000 lines of boilerplate from the project (only
python files), which no developer cares to look at.
SPDX is in common use, particularly in the Linux kernel, and is the
recommended format for Meson's own `project(license: )` field
The title is used only in the sidebar. There is no need to have
"extends" information there. For returned objects the actual name is not
meaningful so it's better to use the long name. For builtin objects the
name is important because that's the global variable name.