Added `api.check.is_conversation_view()` and `api.get.displayed_email_data()` for conversation view turned off.

Added `api.tools.extract_email_address(str)` and `api.tools.extract_name(str)` for utility.
Made sure name is never undefined in people_involved (in convo off view).
api.check.is_conversation_view() looks for the convo-view flag.
api.get.displayed_email_data() excludes deleted emails, or non-deleted emails when reading from trash.
api.check.is_conversation_view() returns true if no flag found.
Simplified api.check.is_conversation_view() check.
Updated README.
Updated README.
Solved conflict merging master into conversation-off.
Merge pull request #51 from g8g3/conversation-off

Added `api.get.displayed_email_data()`