qtgui: fixed problem with new volk avx multiply kernel.

Was calling _a version of kernel, but the window is a std::vector, which is not guaranteed to be 32-byte aligned.
tags: adds get_tags_in_window helper function for handling tags. Also updates some docs.
Merge branch 'maint'
cmake: updates (basically reverts) commit 3c44ba0687b08.

ICE 3.4.2 must be run with GCC 4.6 or less. Versions >= 4.7 will not work. All versions of GCC tested compile ICE 3.5.0/1. This check tests the version of GCC and if it is /NOT/ less than 4.6 (and therefore 4.7 or greater), then issue an error and disable ControlPort.
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'
qtgui: timing is handled in the blocks; removing the qt timer.

This update dramatically reduces the X server overhead of the QT sinks.
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.
qtgui: fixed call to _a version of volk kernels for waterfall plots.

(same fix tha was applied to freq_sinks in bf6d843ebde3a36).
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.
grc: fix error message in console when using qtgui blocks
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'
updated
updated