qtgui: increased max tabs from 5 to 20 in tab widget
Merge branch 'maint'
cmake: increased revision to 3.7.5.1 for maintenance release
Merge branch 'maint'
blocks: adding a tanh lut for control_loop blocks to use.
digital: adding use of tanh and snr info to costas loop.
qtgui: fixes issue with 1-off because of added history of 2.
Merge branch 'maint'
Merge branch 'costas_snr'
qtgui: fixes issue of setting min/max when using qwt < 6.1.0.
Merge branch 'maint'
blocks: fixed use of "not" for "!".
qtgui: allow float freq plot to only plot positive half of spectrum.
qtgui: fixed problem with setting fft size and averaging of the float waterfall at runtime.
qtgui: allow toggle to only show positive half of waterfall spectrum.
qtgui: fixed comment.
qtgui: added triggering to freq sinks.

- Trigger off power (norm/auto): if any power bin in the FFT is greater than the level, output.

- Trigger off tag: if the given tag is found, take FFT from that triggered sample.

- Simplifies work funciton by relying on set_output_multiple so we always work off a multiple of FFT-length slices.
qtgui: removes use of outputsize in freq sinks.

- Was a bit confusing and caused use of different FFT sizes than the user specificed; often resulting in 1 more than a power of 2 for standard values (would be slightly less efficient).

- The problem was more in the _resetXAxisPoints calculation; I think this gets the desired effect of the frequency plots.
qtgui: removing malloc/free in fft function; doing once in ctor and when fftsize changes, instead.
Merge branch 'maint'