+++ /dev/null
-necessary
-=========
-
-delete halfway-built output files when interrupted
-
-frosting
-========
-
-when we've been waiting for commands for more than a second
-with no output, print some "still waiting for xyz" text
-
-if command line for an output changed, no need to even stat
-the output, just mark it for rebuilding immediately.
-
-"explain" mode that shows why we're building a file
-
-"one file" mode that builds only outputs of a single file
-
-adjust to system load dynamically
-
-compute etas on builds using logged timing info
- how does parallelization fit in?