Look for license headers in some range at the top of files

[mlegner]

Currently, the tool requires the license header at the very top of files. However, in some cases the first line(s) of a file MUST have a particular content for some reason. A typical example is something like #!/bin/bash for shell scripts.

It would be great if the tool would look for the license header within some range of the top (maybe configurable?), at least when running it with check. That would allow adding the header manually for files where it shouldn't be at the very top but not having to explicitly ignore those.