Keeping the license as part of every file bloats up the files
unnecessarily and introduces an additional overhead to the creation of
new modules.
Since cargo already provides excellent dependency management, most of
the code-reuse of Alacritty should occur through Rust's dependency
management instead of copying it source.
If code is copied partially, copying the license from the main license
file should be just as easy as copying from the top of the file and
making some adjustments based on where it is used is likely necessary
anyways.