This patch makes the function signature of the on_bookmark_click handler
more readable by replacing `Mod_None` with `OpenInNewTab::No` and
`Mod_Ctrl` with `OpenInNewTab::Yes`.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
