Currently, to specify an input source map, one uses the global "orig" option of SourceMap().
This works if there is a single source, but does not allow to specify multiple input source maps when multiple files are provided through multiple calls to parse().
The requested option to parse() would solve this issue, allowing to have some files with input source maps, and some without.
A typical use case is when some source files are Coffee script. There is one individual source map for each compiled coffee source.
This is linked to issue #145 but this one is about the API.
Closing as duplicate of #145, now that CLI depends on minify().