[Discuss-gnuradio] Updated GRC categories - prep for v3.7

[Tom Rondeau]

The next stage of preparing for GR v3.7 is work to make the GRC
component structure more sane. By duplicating blocks, we also made it
more difficult to use the GRC category tree because of duplication
there, too.

But now that we're satisfied that the blocks are working and that we
have transitioned most  of the GRC components out of gnuradio-core,
we've restructure the components.

* We removed all of the old blocks from the GRC component tree.

* This does _not_ remove the blocks from GRC, so this does not affect
GRC apps already created.

* The change affects how we find blocks, and the blocks in the
category tree are now (almost) all from 3.7.

* We have changed the category names and reorged all of the blocks, so
it might take a little bit of getting used to. But we feel the new
categorization is more intuitive.
  ** The next section shows the new category names used.

* When using the component tree, almost all the blocks listed there
are the new blocks for 3.7.

* When opening your GRC files now, if you are using a block that is
from 3.6, the name will be: "Block name (old)".
  ** This is to make it clear that you are using a pre-3.7 block.

* The (old) name is to help identify where you can update to a new 3.7
block in your flowgraph.
  ** This will help prepare you for the conversion to v3.7

* The search box will return all blocks found, including the (old)
blocks, so you can still get access to these, if you really want.


Note. Not all GRC blocks were converted this way on master. A lot of
the hierarchical blocks that had a GRC component were not necessarily
moved over to the new components on the master branch. So you might
still find a few problems when opening up old GRC files in 3.7.

To see the list of blocks that are still being pulled in the old way,
you can look at grc/blocks/block_tree.xml in the source code, or it is
installed into ${prefix}/share/gnuradio/blocks/block_tree.xml.

This should really help with transitioning your work to 3.7 when you
need to and in the meantime will not affect your current, running
systems in anyway but looks.


Tom