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'