Support for multiple input script files

[tmcphillips]

Users need to be able analyze scripts that span multiple source files (in single or multiple directories). A proposal for implementing an initial, language-independent iteration of this feature is as follows:

• Allowing multiple source files to be listed on the command line (explicitly or via wildcard expressions).
• By listing relevant source files in the YW project file (see issue #16), again either explicitly or via wildcard-containing expressions.
• By referring to additional YW project files (possibly in different directories) which themselves refer to one or more source files.

When multiple script files are processed, one of these script must be identified as the top-level script. A command line option (and corresponding project-file default setting) will allow this script to be identified; in its absence the first file listed on the command line (or in the project file) will be taken as the top-level script.

Language-specific support for automatically analyzing files that are referred to directly or indirectly via include/import directives will not be implemented at this time.

[sycao5]

This feature lets yesWorkflow can process a project containing multiple files.