grc: removed 'old' grc keys from block_tree.

This does not remove the actual GRC files, just how we find them in the block tree structure of GRC.

Renames all blocks not updated to 3.7 style as "(old)" in name.
docs: updating Doxygen categories for all blocks.

Block categories in Doxygen now match where they are in GRC's category tree.
grc: adding sorting ability to GRC category tree.
Merge branch 'master_grc_components'
docs: make Doxygen depend on generated includes before building.
docs: Added a target for trellis generated includes for Doxygen to depend on.
build: only ever include "config.h" in source (.cc) files.
filter: added exception when using interpolating filter with no taps provided.
Merge branch 'maint'