Have a BLOG_POSTER permission

[Alec Thomas]

I think this would be useful, just to prevent random people clicking on the "new blog post" link.

[John Hampton]

(In [609]) * Added BLOG_POSTER permission. Closes #280.

• Added [[BlogPost(title=Link name)]] to provide for renaming the macro link. Closes #281

[John Hampton]

The only caveat of the fix is that a blank line appears if a user without BLOG_POSTER perms visits a page that has the [[BlogPost()]] macro

This is due to the fact that wiki_to_html calls the Formatter with escape_lines = True. So a [[BR]] macro gets appended to each macro line. So if the macro returns nothing, a <br /> tag is still inserted into the HTML. Unfortunately, the fix is non-trivial du to the usage of regexes. So that's just how things will have to be for right now.