Remove Makefile.am/config.in, etc
Turn on -Wall -Werror, and fix warnings.
Loading text, bug fixes

* plugins were destroyed+recreated when changing certain styles:
  position:absolute, -webkit-flex, etc. Now we modify the embed using
  JavaScript instead of CSS.
* Ignoring HandleDocumentLoad means we load the .love file twice. It's
  cached the second time, but still.
* Using the HandleDocumentLoad URLLoader means we don't get download
  progress -- we know how much we've read, but not the maximum size. :(
  So we display a loading message instead of a progress bar.
* Need to make sure we don't spin up the MainLoop until the
  HandleDocumentLoad is called, or we'll try to download a second time.
  We detect this by looking for love_src in the embed attributes.