Add/remove license to/from source files

Utility to add/remove licenses to/from source files.
Supports processing any combination of globs, files, and directories (recurse).
Pruning options allow skipping non-licensing files.

licenser uses file identification techniques to infer the format of the license.
Mainly, resolves how text is commented for that particular source file.
Then, string matching is used to detect the presence of the license in source files.
This allows licenser to be an idempotent operation.

Grammar of source file comments

Commented text in source code can be represented by the location and form of the comment symbols (symbol) and whitespaces (ws).
More generally, most commenting syntaxes conform to the following form: