Watch/Workflow mode

[Igmat]

Since main goal of this tool is providing a way to create tests that could be used as documentation with minimal efforts from developers and first step (baset scaffold command was done) I've decided that we have to implement something more intelligent than usual watch mode.

Workflow mode:

1. At start runs all tests and creates dependency graph for each test file;
2. Reruns tests ONLY in case if something from dependency graph was changed (modules cache should be taken into account to have consistent results);
3. Watches creating of source files using --files option from CLI or config file and creates spec for each such file using scaffold functionality;
4. Watches editing of source files - reruns related tests and if edited source file has new export or some of already exported classes/namespaces has new functions, adds new usages to end of spec file;
5. It also has to be compatible with debugging scenarios(#59).