digital: HPD fixes (burst ID tags are no more propagated; buffer sizes are halved to est. max output size)
modtool: bugfixes for in-tree operation (include paths, license, cmake editing)
blocks: fix pdu_to_tagged_stream when saving leftover items
Merge remote-tracking branch 'martin/hpd-modtool-fixes' into maint
digital: fix CID 1090058 and 1043272 in constellation
digital: Fix CID 1043268 and 1043271
grc: fix search entry focus (again)
docs: fixed doxygen warning.
docs: fixed exploring-gnuradio examples and added to doxygen manual.
pmt: added class comparator to rename comperator (to be removed in 3.8).
blocks: prevent alowing more input streams than this block uses.
docs: fixed/modifying/adding documentation for blocks a-l.
digital: fixed warnings about order of initializing variables in constellation.
cmake: ensure GrPython is included before using methods from it in FindICE.cmake - needed when including only FindICE from OOT modules
cmake: fixes for Apple (specifically; clang generically) to handle some missing AVX instructions.
modtool: dashes no longer allowed in modnames at all (fixes #619)
Update revision to 3.7.2.1
Fix a typo that prevents the Max block from working in GNU Radio Companion
when its IO Type is set to Short.
volk: removing duplicate entry for volk_8i_convert_16i.
volk: using union for float to int conversion in volk_32f_invsqrt_32f.

Removes warning about type-punned pointer. Also, produces noticeable speed increase using GCC, though slightly slower with clang.