Auto merge of #585 - vvuk:wrench, r=glennw

Add Wrench to WebRender

This moves Wrench to WebRender.  It can now replay binary recordings (replaces the wr-replay tool, though I haven't removed that one), show frames from YAML, and write YAML while replaying a binary recording.  The YAML stuff is very much WIP, but what's there works and can be built on top of.

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Author: bors-servo

.gitignore

@@ -1,4 +1,4 @@
 target/
 *~
 *#
-
+.vscode

.travis.yml

@@ -16,3 +16,4 @@ script:
   - (cd webrender && cargo test --verbose)
   - (cd sample && cargo test --verbose)
   - (cd replay && cargo test --verbose)
+  - (cd wrench && cargo test --verbose)