Add a lookup table to the encoder inner loop for byte mode only
(used by the ATSC transmitter).
Windows compatibility fixes

* cmake: use CMake's internal variables for compiler info
* volk: void* can't be used for pointer arithmetic in MSVC, so cast
blocks: tagged_stream_to_pdu now uses logic from tagged_stream_block, also more QA
blocks: adding abs_xx block/template
Merge remote-tracking branch 'martin/pdu-to-tsb'
Merge branch 'maint'
tags: adds get_tags_in_window helper function for handling tags. Also updates some docs.
Merge branch 'maint'
runtime: adds a gr.tag_utils.python_to_tag to convert formatted dicts/lists/tuples to tag_t objects.

blocks: adds documentation to vector_source block on how to use the python_to_tag to emit tags with the data stream.
Merge branch 'maint'
Merge branch 'maint'
qtgui: adds ability to set the graphics style rendering of the qtgui sinks.

Set through gr-qtgui.conf prefs file. Documented in QT GUI section of manual.
Merge branch 'maint'

Conflicts:
	gr-qtgui/lib/waterfall_sink_c_impl.cc
	gr-qtgui/lib/waterfall_sink_f_impl.cc

Conflict due to white space issues.
build: moving the location of the config.h file in the build tree so we can access it in sources as gnuradio/config.h.

Also uses the config.h to pull out if we've defined GR_PERFORMANCE_COUNTERS to handle the setup_pc_rpc function if perf counters are/are not compiled in.
cmake: Adds GR_CTRLPORT as a define in the root directory to populate config.h properly.
Merge branch 'maint'
blocks: allow subtract block to take a single input to invert the sign.
blocks: allows null source/sink to output/input multiple streams.

Updats xml files to allow this and to set bus port connection vector to group ports.
filter: adds a ccf version of the fft filter.

Taps are converted to complex still, so no computational savings here. Just for convinience of setting taps (mostly in c++).
filter: use fft_filter inside pfb_decimator.

Depending on the decimation rate and filter size, filtering with time domain or freq domain can be slower/faster and rotating using expj or fft can be slower/faster. This enables users to decide which features to use.