Add an Intent so other apps can use Catlog to send logcat info via email

Sorry, my GitHub skills are approx. zero. I think this pull request probably includes the one I sent you yesterday.

Anyway, I've added an Intent to Catlog so other apps can use it to send logcat info by email. It's not as good as I was hoping - the user is still prompted by the email program to click on Send. I would prefer that it was completely automatic, but that is apparently not possible, or at least not easy.

Hope you can use this.