Fixes issue #38

This changeset implements postfix comments "///<" for most elements:

 * @property
 * -/+ method declaration
 * -/+ method definition
 * NS_ENUM/NS_OPTION typedef
 * NE_ENUM/NS_OPTION keys

Multi line postfix comments are supported within above elements.

Postfix comments are ignored for classes, interfaces, protocols, etc.

If both, a normal (prefix) and a postfix comment is available, the postfix
comment is ignored.
Merge pull request #459 from dhoepfl/postfix

Fix for issue #38: Allow single-line comment *after* the documented line