Merge pull request #63 from Erok21/master

Add getInbox, fix naming on messagesurl
Added captcha handling for Subreddit.Submit(Text)Post
Make SubmitData and derivatives internal
Add default captcha handler
Update post data classes to use properties, update webagent to read internal properties
Merge pull request #64 from Sharparam/patch-4

Added captcha handling for Subreddit.Submit(Text)Post
Update Post.Comment()
Fix unix timestamp conversion
Expose the webagent.

I need to use the webagent for arbitrary calls (like get a wiki page,
etc.)
Reddit class assigned created unused variable.
Add SetFlair to Post.cs

Allows users to set a link's flair
Add filtering when retrieving comments and posts by user
Throw ArgumentOutOfRangeException for invalid limit
Added sender to Comments and added const value.
Changed ushort into int
Add GetPrivateMessages
Fix issues with special subreddits
Add getInbox, fix naming on messagesurl
Add SentUTC to PrivateMessage
Added captcha handling for Subreddit.Submit(Text)Post