chore: migrate Travis CI to container-based builds and update README links

- Switch Travis CI from sudo-based apt-get to addons.apt.packages for gcc-multilib
- Enable container-based builds with `sudo: false`
- Update README.md call-to-action links to point to getting-started and browser playground
- Replace `printList_` with `printAll` in IO class and remove redundant `IO.` prefixes
- Add IO.read() method documentation and update IO.print docs for up to 16 arguments
- Reorganize community page with Libraries, Language bindings, and Tools sections
- Add wrenjs JavaScript binding and Sublime Text syntax highlighting
- Fix typo "no where" to "nowhere" in fibers documentation
- Add indentation to preprocessor defines in wren_common.h for consistency
- Remove unreachable `return 0` after UNREACHABLE() in wren_compiler.c
- Fix Windows color output by wrapping text in str() in test script

doc/site/index.markdown

@@ -41,8 +41,9 @@ a familiar, modern [syntax][].
     and [an easy-to-use C API][embedding]. It compiles cleanly as C99, C++98
     or anything later.
 
-If you like the sound of this, [give it a try][try]! Even better, you can
-[contribute to Wren itself][contribute].
+If you like the sound of this, [let's get started][started]. You can even try
+it [in your browser][browser]! Excited? Well, come on and [get
+involved][contribute]!
 
 [syntax]: syntax.html
 [src]: https://github.com/munificent/wren/tree/master/src
@@ -51,5 +52,6 @@ If you like the sound of this, [give it a try][try]! Even better, you can
 [classes]: classes.html
 [fibers]: fibers.html
 [embedding]: embedding-api.html
-[try]: getting-started.html
+[started]: getting-started.html
+[browser]: http://ppvk.github.io/wren-nest/
 [contribute]: contributing.html