support for more file types?

I've a project with a bunch of non-{go,bash,makefile,dockerfile} files in them (as well as some of each of those four). It'd be great if the support for different file types could be more flexible, e.g. a way to specify a mapping from globs to filenames such as `ltag -map "*.go=go.txt" -map "*.java=java.txt"`.

As a side effect something like that would allow the files to be consolidated into one for each "comment style" rather than being per language, e.g. `ltag -map "*.go=c-style.txt" -map "*.java=c-style.txt" -map "*.sh=shell-style.txt"`.