Merged r11377:11390 from jcorgan/usrp-headers in to trunk.

Merged r11377:11390 from jcorgan/usrp-headers in to trunk.

* Public USRP(1) header files are now in their own source directory
  and install into $(includedir)/usrp.  This was done to avoid name
  clashes in the top-level include directory.

  Only users who are developing directly to libusrp in C++ are
  affected; the GNU Radio C++ and Python APIs are unchanged.

  The simple change required by this update is to change:

  #include <usrp_*.h>

  to #include

  <usrp/usrp_*.h>

  ...in your source code.

* Removed usrp-inband code from tree (put into limbo directory.)
  This code has become unmaintained and has started to suffer
  from bitrot.  A checkpoint tag has been made for anyone still
  needing to use it:

  http://gnuradio.org/svn/gnuradio/tags/checkpoints/trunk-20090708-pre-usrp-reorg

  The plan during the 3.2->3.3 development cycle is to replace the
  functions done by the in-band code with extensions to the existing
  gr-usrp blocks using the new message passing architecture.

  The USRP hardware FPGA code that provided the inband interface
  has not been removed; however, it too has become unmaintained and
  will likely be rewritten/replaced during the 3.3 timeframe.

The trunk passes distcheck.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@11394 221aa14e-8319-0410-a670-987f0aec2ac5