USRP2 code now in trunk

Just an FYI for those of you using the trunk version of the software
instead of the official release–

The USRP2 host code, firmware, and FPGA code have been merged into the
trunk (r9528). This is a large amount of code, so be prepared for the
next time you update.

That being said, the code is not yet ready for prime time. The host
code will build on Linux systems; for others, it will be deselected
during build configuration. You need to have installed the Xilinx
Microblaze compiler (mb-gcc) in order to build the firmware, otherwise
this will be deselected as well. Finally, Xilinx ISE is needed to
compile the FPGA code, though this is not part of the build process

This merge was done a little earlier than normal for a development
branch, but it was important to get this in to the current trunk to
avoid the developer branch going “stale”, and to help keep all four
(usrp2 host, firmware, fpga, and gr-usrp2) in sync. There are number of
things that are incomplete, and the API is still subject to change.

As usual, if the trunk starts having problems building for you, please
let us know asap.

The above does not affect anyone using the official release tarballs or
the SVN repository release branch.