OS X: don't use CompiledMOFilePresenter if not sandboxed

addFilePresenter logs an error when calling it (unnecessarily) in
non-sandboxed apps.
Update author email address
Minor README clarifications about git
Fix Preferences crash when adding new extractor

Due to changes for OS X preferences, removing the newly added extractor
on cancel would crash. Fix by disabling data transfer on window
activation when editing the extractors.
OS X: Fix runtime linked search path

Change it to include frameworks. This is the recommended deployment
method and one that the updated Sparkle framework now requires.
OS X: Set PATH environment in Info.plist

Apps launched via Dock or Finder (i.e. through Launch Services) don't
respect ~/.profile environment variables in modern versions of OS X.
There's no way to adjust the PATH that would be simple enough for
"normal" users to use. Unfortunately, this breaks running custom
extractors.

To mitigate this for the common case, add commonly used paths,
/usr/local/bin (Homebrew, various tools like npm or gem) and
/opt/local/bin (MacPorts) to LSEnvironment so that Poedit can always use
them.

See e.g. https://github.com/gmarty/xgettext/issues/35
Fix OS X file associations to work on Yosemite

Poedit used legacy way of specifying supported ways. This still works on
Yosemite in the important ways (such as launching Poedit), but Finder
stopped showing file type description and replaced it with "Poedit
Document".

Don't use deprecated (since OS X 10.5) Info.plist keys. Declare proper
UTIs instead.

See http://www.cocoanetics.com/2012/09/fun-with-uti/