Fixed entry point in package.json
Don't transform non .js files
Update to newest prelude from browser-pack
Use a more elegant approach to overriding the prelude
Use a separate cache when proxyquireify is active

Instead of entirely disabling the browserify cache, just switch to
a different cache each time `proxyquire` is called. This allows
modules like `tape`, which have global state and/or circular
dependencies, to work correctly.

Also, move the require monkeypatching from the transform to the
prelude, wich makes it possible to build code with proxyquireify
even if proxyquireify is not used and is not built into the
bundle. This allows test code to be always built with proxyquireify
even if the module is not included as a dependency.
Enable clientside tests now that they are working
special case for exported functions
Readme update to mention plugin functionality
cleanups and adaptation to plugin API

- adding deprecation warning for old API
- making plugin API default in README and warning about deprecated old
  API
- adapted example to use new API and linked dependencies so no npm
  install is needed to run it
- renamed hack-prelude since it's no longer a hack
- upgrading browserify
- increasing peerdep browserify version range
- adding browerify-tool keyword