Use the reuse tool to get a better grip on licenses used in sixtyfps.
Fix a couple of licenses along the way.
* Uses creative commons for our own logo (commercial use!)
* Fixes some license information found in README files and documents
them with proper .license files.
* Document Apache/MIT for helper_crates/const-field-offset which matches
what its documentaion site says it uses.
* Add a list of licenses that apply to crates we publish and the tooling
we have.
This patch only adds static information and does not contain any tooling
support.
A new attribute implements the Drop mechanics outlined in the Pin
documentation without requiring the use of unsafe on the caller side,
by means of an intermediate PinnedDrop trait.
