Draft: Add file source, tutorial docs, and reference docs
Note: This MR is too multi-faceted and will be split among several Git issues for
- Reference documentation stubs (will be moved to gwsci)
- Pipeline tutorial documentation #90
- Pipeline creation and execution tools #88 (closed)
- New source element for gwf file (convenience wrapper around mux and cache creation) #86 (closed)
- Add pydot to all env #87
- Pipeline visualization tools using dot #89
This MR adds:
- a simple interface for constructing a source element from .gwf files
- Tutorial documentation on pipeline basics (with corresponding juypter notebook)
- Reference documentation on various aspects of the infrastructure (deferred computation, gstreamer, etc.)