Use doubles instead of floats

All of the properties are doubles and we upcast when sending events
anyways, so just make everything doubles
Avoid warnings with WebKit2 in `snapshot`
Cast the decision in WebKit2
Add missing brace
Minimize the number of paths for returning
Set the io_loop to NULL after destroying
Free I/O resources
Always free the path memory
Don't app_cache_directory in WebKit2
Make webkit_view available in WebKit2
Return TRUE from accepted_languages in WebKit2
Merge branch 'dev/misc-cleanups' into mathstuf/next

* dev/misc-cleanups:
  Return TRUE from accepted_languages in WebKit2
  Make webkit_view available in WebKit2
  Don't app_cache_directory in WebKit2
  Always free the path memory
  Free I/O resources
  Set the io_loop to NULL after destroying
  Minimize the number of paths for returning
  Add missing brace
  Cast the decision in WebKit2
  Avoid warnings with WebKit2 in `snapshot`
  Use doubles instead of floats