Refactor TS build and fix testing

This change is largely just moving files with minor tweaks to them to fix,
the rest of the commit is build process changes:

- The addons/ and test/ dirs have been moved to src/
- The build directory has been removed
- TypeScript builds are output in out/, this is where tests are run
- The demo now relies on the dist/ build which is performed as part of ./bin/build
- Addons are now shipped under the ./build directory

src/addons/fullscreen/fullscreen.css

@@ -0,0 +1,10 @@
+.xterm.fullscreen {
+    position: fixed;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    width: auto;
+    height: auto;
+    z-index: 255;
+}