Implemented feature 767 (ready for review & pull)

http://d.puremagic.com/issues/show_bug.cgi?id=767

Implemented -deps switch without an '=file' it prints dependencies to stdout. For module imports the format is the same as for -deps=file, but the line is prefixed with depsImport.

The following dependencies are printed:
depsVersion Any version() found (except standard ones and ones set in the module itself)
depsImport Any imports found (same as -deps=file output, except prefixed with depsImport)
depsFile Any file imports found
depsLib Any libraries specified with pragma(lib)
depsDebug  Andy debug() statements found (except the ones set in the module itself)

The format is extensible, as additional dependencies can be easily added by providing some new prefix depsFOO. Tools can easily grasp what is dependency information, because every line starts with "deps".

This patch is needed for tools like dub for reliable and efficient builds.