[erlang-patches] Cleanup of documentation of the type language

[Kostis Sagonas]

The subject title (and the two commit messages, included below) should 
explain what this patch is about.

==========================================================================
Clean up of documentation of type language

Prompted by noticing that the type language description was a bit vague
in its explanation of the syntax and semantics of bitstring types,
I decided to add this information.  While at it, a general clean up and
rephrasing was performed.  The binary() type is now described as an 
alias, as it should be, and a bitstring() type is also described as a 
built-in alias.
==========================================================================
Add support for printing <<_:_*1>> as bitstring()
==========================================================================

Please include:

   git fetch git://github.com/kostis/otp.git type-doc-cleanup

Kostis